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,,contributions ,,f      ,,! ,,museum   
,,( ,,hi/ory ,,& ,,te*nology3           
,,pap] #f            ,,on ,,! ,,orig9   
,,( ,,clockwork1      ,,p]petual        
,,motion ,,devices ,,& ,,! ,,compass    
,d]ek ,j4 de ,solla ,price              
,,p[] ,,& ,,motion ,,ge>+               
#hc      ,,me*anical ,,clocks           
#hd      ,,me*aniz$ ,,a/ronomical       

,,models                             #hh
      ,,p]petual ,,motion ,,& ,,!       
,,clock ,,be=e ,,de ,,dondi             
#ajh      ,,! ,,magnetic ,,compass ,,z  
,a ,,fell[-,,travel] ,,f ,,*9a      #aaj
            ,,on ,,! ,,orig9 ,,(        
,,clockwork1      ,,p]petual ,,motion   
,,devices      ,,& ,,! ,,compass        
,by ,d]ek ,j4 de ,solla ,price          
,ance/or ( ! me*anical clock has be5    
?\ght by "s to be !  sundial4 ,actually 
^! devices repres5t two diff]5t         
approa*es to  ! problem ( "t-keep+4     
,true ance/or ( ! clock is to be f\nd   
among ! highly complex a/ronomical      
ma*9es :i* man has be5  build+ s9ce     
,hell5ic times to illu/rate ! relative  
motions ( !  heav5ly bodies4    ,?is    
/udy--its f9d+s w be us$ 9 prep>+ !     
,museum's new  hall on ! hi/ory (       
"t-keep+--traces ?is ance/ry back ?r\gh 
#b1jjj ye>s ( hi/ory on ?ree cont95ts4  
,,! ,,au?or3 ,d]ek ,j4 de ,solla ,price 
wrote ?is pap] :ile s]v+ z  consultant  
to ! ,museum ( ,hi/ory & ,te*nology ( ! 

,smi?sonian  ,in/itution's ,unit$ ,/ates
 ,national ,museum4      ,9 ea*         
successive age ?is con/ruction1 hav+    
become    lo/1 is1 by ! ,sun's fav\r1   
aga9 reveal$ to "s "o    or o!r at 8    
pleasure4 7,srya ,siddhnta1 ed4         
,burgess1 xiii1 #ah-ai47      ,,!       
,,hi/ories ( ! me*anical clock & !      
magnetic compass mu/ be  acc\nt$ among/ 
! mo/ tortur$ ( all our ef=ts to und]/& 
!  orig9s ( man's important inv5tions4  
,ignorance has too (t5 be5  replac$ by  
conjecture1 & conjecture by misquotation
 & ! false  au?ority ( common k eng5d]$ 
by ! repetition (  leg5d>y hi/ories f "o
 g5]ation ( textbooks to ! next4 ,9  :at
 foll[s1 ,i c only hope t ! add+ ( a    
/rong new trail &  ! eradication (      
sev]al false & weak] ones w lead u ne>] 
to  a balanc$ & integrat$ und]/&+ (     
m$ieval inv5tion & !  int]cultural      
transmission ( ideas4    ,= ! me*anical 
clock1 p]haps ! greate/ h9drance has be5
 its  treatm5t )9 a self-conta9$ hi/ory 
( "t measurem5t 9 :i*  sundials1        

wat]-clocks & simil> devices assume !   
natural role (  ance/ors to !           
weight-driv5 escapem5t clock 9 ! e>ly   
#ad?  c5tury4#a ,?is view mu/ presume t 
a g5]ally sophi/icat$  k ( ge>+ ant$ates
 ! inv5tion ( ! clock & ext5ds  back to 
! ,classical p]iod ( ,h]o & ,vitruvius &
 su* au?ors  well-kn[n = _! me*anical   
+5uities4    ,fur!rmore1 ev5 if "o      
admits ! use ( clocklike ge>+ be=e !    
exi/5ce ( ! clock1 x is /ill necess>y to
 look = !  indep5d5t inv5tions ( !      
weight-drive & ( ! me*anical  escapem5t4
 ,! fir/ ( ^! may seem comp>atively     
trivial2 anyone  famili> ) ! rais+ (    
heavy loads by means ( ropes & pulley   
c\ld surely recognize ! possibility (   
us+ su* an arrangem5t 9  rev]se z a     
s\rce ( /eady p[]4 ,nev]!less1 ! use (  
?is  device is n record$ be=e its       
association ) hydraulic &  p]petual     
motion ma*9es 9 ! manuscripts ( ,riwn1  
ca4 #abjj1  & its use 9 a clock us+ su* 
a p]petual motion :eel 7m]cury  fill$7 z
 a clock escapem5t1 9 ! a/ronomical     

codices ( ,alfonso  ! ,wise1 ,k+ (      
,ca/ile1 ca4 #abgb4    ,! second        
inv5tion1 t ( ! me*anical escapem5t1 has
 pres5t$  "o ( ! mo/ tantaliz+ (        
problems4 ,)\t d\bt1 ! cr[n &  foliot   
type ( escapem5t appe>s to be ! fir/    
complicat$ me*anical  inv5tion kn[n to !
 ,european ,middle ,ages2 x h]alds our  
:ole age (  ma*9e-mak+4 ,yet no trace   
has be5 f\nd ei!r ( a /eady evolution  (
 su* escapem5ts or ( _! inv5tion 9      
,europe1 ?\gh !  a/ronomical clock p[]$ 
by a wat] :eel & gov]n$ by an           
escapem5t-l device _h be5 elaborat$ 9   
,*9a = sev]al  c5turies be=e ! fir/     
appe>ance ( our clocks4 ,we mu/ n[      
rehe>se a revis$ /ory ( ! orig9 ( !     
clock z x has be5  sugge/$ by rec5t     
rese>*es on ! hi/ory ( ge>+ & on ,*9ese 
& o!r a/ronomical ma*9es4 ,aft] ?is we  
%all = ! fir/ "t  pres5t evid5ce to %[ t
 ?is /ory is curi\sly relat$ to t (  !  
,p]petuum ,mobile1 "o ( ! great *im]as (
 sci5ce1 t came  f its m$ieval orig9 to 
play an important "p 9 m rec5t          

developm5ts ( en]getics & ! f\ndations (
 !rmodynamics4#b ,x  is a curi\s        
mixture1 all ! m s because1 tangl$      
inextricably 9  x1 we %all f9d ! mo/    
important & e>lie/ ref]5ces to ! use  ( 
! magnetic compass 9 ! ,we/4 ,x seems t 
9 revis+ !  hi/ories ( clockwork & !    
magnetic compass1 ^! consid]ations  (   
p]petual motion devices may provide "s  
mu* ne$$ evid5ce4    ,illu/ration3      
,figure #a4--;,,framework ,,/ructure ,,(
 ,,! ,,a/ronomical ,,clock  ( ,giovanni 
de ,dondi ( ,padua1 ,a4,d4 #acfd4       
,p[] & ,motion ,ge>+    ,x may be       
readily accept$ t ! use ( too!d :eels to
 transmit  p[] or turn x ?r\gh an angle 
0 widespread 9 all cultures sev]al      
c5turies be=e ! beg9n+ ( our era4       
,c]ta9ly1 9 classical times  !y 7       
already famili> to ,ar*im$es 7born #bhg 
,b4,c471#c & 9  ,*9a actual examples (  
:eels & m\lds = :eels dat+ f !  #d?     
c5tury ,b4,c4 h be5 pres]v$4#d ,x might 
be rem>k$ t  ^! ma*9e ge> :eels are     
*>act]iz$ by hav+ a r\nd numb]  ( tee?  

7examples ) #af1 #bd & #dj tee? are     
kn[n7 & a %ank )  a squ>e hole :i* fits 
)\t turn+ on a squ>$ %aft4 ,ano!r       
rem>kable feature 9 ^! e>ly ge>s is !   
use ( rat*et-%ap$  tee?1 sometimes ev5  
twi/$ helically s t ! ge>s resemble     
worms  int]me%+ on p>allel axles4#e ,!  
exi/5ce ( w9dmills &  wat]mills te/ifies
 to ! g5]al famili>ity1 f classical     
times  & ?r\gh ! middle ages1 ) ! use ( 
ge>s to turn p[] ?r\gh  a "r angle4     
,illu/ration3 ,figure                   
#b4--;,,a/ronomical ,,clock ( de ,dondi1
 %[+  ge>+ on ! dial = ,m]cury &        
escapem5t cr[n :eel4 ,ea* ( !  sev5 side
 walls ( ! /ructure %[n 9 figure #a 0   
fitt$ ) a  dial4    ,grant$1 !n1 ?is use
 ( ge>s1 "o mu/ gu>d aga9/ any          
conclusion  t ! f9e-me*anical use ( ge>s
 to provide special ratios (  angul>    
movem5t 0 simil>ly g5]al & widespread4  
,x is cu/om>y  to adduce "h ! evid5ce ( 
! hodomet] 7taximet]7 describ$ by       
,vitruvius 7#a/ c5tury ,b4,c47 & by ,h]o
 ( ,alex&ria 7#a/ c5tury  ,a4,d47 & !   

+5i\s automata also describ$ by ?is     
latt] au?or  & 8 ,islamic foll[]s4#f ,"o
 may also cite ! use ( ! r$uction  ge>  
*a9 9 p[] ma*9]y z us$ 9 ! ge>$ w9dlass 
(  ,ar*im$es & ,h]o4    ,un=tunately1   
ev5 ! mo/ complex automata describ$ by  
,h]o & by  su* au?ors z ,riwn conta9    
ge>+ 9 no m ext5sive context  ?an z a   
means ( transmitt+ action ar\nd a "r    
angle4 ,z = !  w9dlass & hodomet]1 !y d1
 x is true1 conta9 :ole s]ies (  ge>s   
us$ 9 /eps z a r$uction me*anism1       
usually = an  extraord9>ily high ratio1 
b "h ! te*nical details are s  e!rial t 
"o mu/ d\bt :e!r su* devices 7 actually 
realiz$  9 practice4 ,?us ,vitruvius    
writes ( a :eel #d feet 9 diamet] &     
hav+ #djj tee? be+ turn$ by a #a-too!d  
p9ion on a c>t axle1 b  x is v d\btful  
:e!r su* small tee?1 necess>ily sep>at$ 
by  ab\t #c_/h in*1 w\ld h ! requisite  
rugg$ness4 ,aga91 ,h]o  m5tions a :eel (
 #cj tee? :i*1 because ( imp]fections1  
might ne$  only #bj turns ( a s+le helix
 worm to turn x6 ,su* /atem5ts behove   

caution & "o mu/ consid] :e!r we h be5  
misl$ by !  #af?- & #ag?-c5tury editions
 ( ^! au?ors1 conta9+  recon/ructions n[
 (t5 cit$ z au?oritative b !n s]v+ z    
work+ diagrams = practical use 9 t age  
:5 ! clock 0  already a famili> &       
complex me*anism4 ,at all ev5ts1 ev5 if 
"o  admits )\t sub/antial evid5ce t su* 
ge> r$uction devices  7 famili> f       
,hell5i/ic times onw>ds1 !y c h>dly s]ve
 z  m ?an v di/ant ance/ors ( ! e>lie/  
me*anical clocks4          ,me*anical   
,clocks    ,be=e proce$+ to a discussion
 ( ! controv]sial evid5ce :i*  may be   
us$ to bridge ?is gap betwe5 ! fir/ use 
( ge>s & !  fully-develop$ me*anical    
clock we mu/ exam9e ! o!r side ( ?is    
gap4 ,rec5t rese>* on ! hi/ory ( e>ly   
me*anical clocks has  demon/rat$ c]ta9  
peculi>ities mo/ relevant to our pres5t 
argum5t4      ,,! ,,european ,,tradition
    ,if "o is to e/abli% a t]m9us ante  
quem = ! appe>ance ( !  me*anical clock 
9 ,europe1 x w\ld appe> t #acfd is a mo/
  reasonable date4 ,at t "t we h ! v    

full me*anical &  hi/orical mat]ial     
conc]n+ ! horological ma/]piece built by
  ,giovanni de ,dondi ( ,padua1#g &     
probably />t$ z e>ly z #acdh4 ,x  might 
well be possible to set a date a few    
decades e>li]1 b 9  g5]al z "o proce$s  
backw>ds f ?is po9t1 ! evid5ce becomes  
increas+ly fragm5t>y & unc]ta94 ,!      
greate/ s\rce ( d\bt  arises f !        
confusion betwe5 sundials1 wat]-clocks1 
h&-/ruck  "t bells1 & me*anical clocks1 
all ( :i* are cov]$ by ! t]m  horologium
 & its v]nacul> equival5ts4             
,tempor>ily po/pon+ ! consid]ation (    
evid5ce prior to ca4  #acej1 we may take
 ,giovanni de ,dondi z a />t+ po9t &    
trace a  virtually unbrok5 l9eage f 8 "t
 to ! pres5t day4 ,"o may  foll[ !      
spread ( clocks ?r\gh ,europe1 f l>ge   
t[ns to small  ones1 f ! ri*] ca!drals &
 abbeys to ! less weal?y  *ur*es4#h ,!re
 is ! transition f ! t[]                
clocks--%[pieces  ( great               
in/itutions--to ! simple *amb] clock    
design$ = dome/ic  use & to ! small]    

portable clocks & /ill small] & m       
portable pocket wat*es4 ,9 me*anical    
ref9em5t a simil> cont9uity  may be     
not$1 s t "o sees ! cumulative effect ( 
! introduction  ( ! spr+ drive 7ca4     
#adge71 p5dulum control 7ca4 #afej71 & !
  an*or escapem5t 7ca4 #afhj74 ,!       
transition f de ,dondi to !  mod]n      
*ronomet] is inde$ basically cont9u\s1 &
 ?\gh mu*  rese>* ne$s to be done on    
special topics1 x has an hi/orical unity
  & seems to con=m = ! mo/ "p to ! g5]al
 patt]n ( /eady  me*anical improvem5t   
f\nd else:]e 9 ! hi/ory ( te*nology4    
,illu/ration3 ,figure #c4--;,,g]man     
,,wall ,,clock1 ,,probably ,,ab\t #adej1
  %[+ ! deg5]ation 9 complexity f t ( de
 ,dondi's clock4    ,mo/ rem>kable h[ev]
 is ! e>lie/ p]iod ( ?is seem+ly /eady  
evolution4 ,side by side ) ! advances   
made 9 ! e>lie/ p]iod  ext5d+ = less ?an
 two c5turies f ! "t ( de ,dondi "o may 
see a spectacul> process ( deg5]ation or
 devolution4 ,n only is de  ,dondi's !  
e>lie/ clock ( :i* we h a full &        

tru/wor?y  acc\nt1 x is also f> m       
complicat$ ?an any o!r 7see figs4 #a1   
#b7  until comp>atively mod]n times6    
,moreov]1 x 0 n an exceptional  freak4  
,!re 7 o!rs l x1 & "o _c !re=e reject z 
accid5tal ?is process ( deg5]ation t    
occurs at ! v  beg9n+ ( ! c]ta9 hi/ory (
 ! me*anical clock 9 ,europe4    ,on !  
basis ( su* evid5ce ,i h sugge/$        
else:]e#i t !  clock is n\ght b a fall5 
angel f ! _w ( a/ronomy4 ,!  fir/ great 
clocks ( m$ieval ,europe 7 design$ z    
a/ronomical  %[pieces1 full ( complicat$
 ge>+ & dials to %[ ! motions (  ! ,sun1
 ,moon & planets1 to exhibit eclipses1 &
 to c>ry ?r\gh !  involv$ computations (
 ! ecclesia/ical cal5d>4 ,z su* !y 7    
comp>able to ! orr]ies ( ! #ah? c5tury &
 to mod]n  planet>iums2 t !y also %[$ ! 
"t & rang x on bells 0  almo/ incid5tal 
to _! ma9 function4 ,"o mu/ n neglect1  
too1  t x 0 9 _! glorification ( !      
rationality ( ! cosmos t  !y _h _!      
greate/ effect4 ,?r\gh mill5iums (      
civilization1  man's und]/&+ ( cele/ial 

ph5om5a _h be5 ! v p9nacle (  8         
intellect1 & !n z n[ popul> exhibition (
 ?is sort 0 j  z necess>y1 z /rik+1 & z 
impressive4 ,"o does n h to g  f> to see
 h[ ! p>aph]nalia ( ^! e>ly great       
a/ronomical  clocks _h great influ5ce on
 philosoph]s & !ologians & on poets  su*
 z ,dante4    ,x is ! !sis ( ?is "p ( my
 argum5t t ! ord9>y  "t-tell+ clock is  
no affiliate ( ! o!r simple "t-tell+    
devices su* z sundials1 s& glasses & !  
elem5t>y wat] clocks4  ,r x %\ld be     
consid]$ z a deg5]ate bran* f ! ma9 /em 
( me*aniz$ a/ronomical devices 7,i %all 
call !m protoclocks71 a  /em :i* c boa/ 
a cont9u\s hi/ory fill+ ! gap betwe5 !  
appe>ance ( simple ge>+ & !             
complications ( de ,dondi4 ,we %all     
return to ! discussion ( ?is ma9 /em    
aft] analyz+ ! v  rec5tly discov]$      
p>allel /em f m$ieval ,*9a1 :i*         
reproduc$  ! same evolution ( me*aniz$  
a/ronomical devices & incid5tal  "t     
tell+4 ,( ! greate/ significance1 ?is   
/em reveals !  crucial indep5d5t        

inv5tion ( a me*anical escapem5t1 a     
feature n  f\nd 9 ! ,european /em 9     
spite ( c5turies ( int5sive hi/orical   
rese>* & ef=t4      ,,! ,,*9ese         
,,tradition    ,= ?is section ,i am     
privileg$ to draw ^u a ?rill+ rese>*    
project c>ri$ out 9 #aief at !          
,univ]sity ( ,cambridge by a team       
consi/+ ( ,dr4 ,joseph ,ne$ham1 ,dr4    
,wang ,l+1 & myself4#aj ,9 !  c\rse (   
?is "w we translat$ & comm5t$ on a s]ies
 ( texts  mo/ ( :i* _h n hi!rto be5 made
 available 9 a ,we/]n tongue  &1 ?\gh   
well kn[n 9 ,*9a1 _h n be5 recogniz$ z  
important  = _! horological cont5t4 ,!  
key text ) :i* we />t$ 0  ! ,hs9 ,i     
,hsiang ,fa ,yao1 or ,new ,design = a   
7me*aniz$7 ,armill>y  7sph]e7 &         
7cele/ial7 ,globe1 writt5 by ,su ,sung 9
 ,a4,d4 #ajij4 ,!  v full hi/orical &   
te*nical description 9 ?is text enabl$ u
  to e/abli% a gloss>y & basic und]/&+ (
 ! me*anism t  lat] enabl$ u to int]pret
 a :ole s]ies ( simil>1 ?\gh less       
ext5sive texts1 giv+ a hi/ory ( prior   

developm5t ( su* devices  go+ back to ! 
introduction ( ?is type ( escapem5t by  
,i-,hs+ &  ,liang ,l+-tsan1 9 ,a4,d4    
#gbe1 & to :at seems to be ! orig9al (  
all ^! ,*9ese a/ronomical ma*9es1 t     
built by ,*ang ,hng ca4  ,a4,d4 #acj4   
,fill+ ! gaps betwe5 ^! l&m>ks are      
sev]al o!r  simil> texts1 giv+ ample    
evid5ce t ! ,*9ese developm5t is        
cont9u\s &1 at lea/ f ,*ang ,hng onw>ds1
 l>gely indep5d5t (  any transmissions f
 ! ,we/4    ,s f> z we c see1 ! beg9n+ (
 ! *a9 9 ,*9a 7z inde$ 9  ! ,we/7 0 !   
mak+ ( simple /atic models ( ! cele/ial 
sph]e4 ,an armill>y sph]e 0 us$ to      
repres5t ! *ief imag9>y  circles 7e4g41 
equator1 ecliptic1 m]idians1 etc471 or a
 solid  cele/ial globe on :i* su*       
circles c\ld be drawn1 toge!r ) !       
con/ellations ( ! fix$ />s4 ,! :ole     
app>atus 0 !n m\nt$  s t x 0 free to    
revolve ab\t its pol> axis & ano!r r+ or
  a cas+ 0 add$1 ext]nal & fix$1 to     
repres5t ! horizon t  provid$ a datum = 
! ris+ & sett+ ( ! ,sun & ! />s4    ,9 !

 next /age1 rea*$ v soon aft] ?is1 !    
rotation ( !  model 0 arrang$ to proce$ 
automatically in/ead ( by h&4 ,?is 0    
done1 we believe1 by us+ a sl[ly revolv+
 :eel p[]$ by dripp+  wat] & turn+ !    
model ?r\gh a r$uction me*anism1        
probably  involv+ ge>s or1 m reasonably1
 a s+le l>ge ge> turn$ by a  trip lev]4 
,x did n matt] mu* t ! "t-keep+         
prop]ties 7  poor 9 ! long run2 ! model 
mov$ by itself & ! great wond]  0 t x   
agre$ ) ! obs]v$ heav5s l ! two halves (
 a  tally4    ,9 ! next1 & ess5tial1    
/age ! turn+ ( ! wat] :eel 0  regulat$  
by an escapem5t me*anism consi/+ ( a    
weighbridge &  trip lev]s s arrang$ t ! 
:eel 0 held 9 *eck1 scoop by  scoop1    
:ile ea* scoop 0 fill$ by ! dripp+ wat]1
 !n releas$  by ! weighbridge & all[$ to
 rotate until *eck$ aga9 by !  trip-lev]
 arrangem5t4 ,its action 0 simil> to t (
 ! an*or  escapem5t1 ?\gh its p]iod (   
repose 0 mu* long] ?an its p]iod  (     
motion &1 ( c\rse1 its "t-keep+         
prop]ties 7 controll$ n  only by !      

me*anics ( ! device b also by ! rate (  
fl[ ( !  dripp+ wat]4    ,! ,*9ese      
escapem5t may ju/ifiably be reg>d$ z a  
miss+ l9k1  j halfway betwe5 ! elem5t>y 
clepsydra ) its /eady fl[ (  wat] & !   
me*anical escapem5t 9 :i* "t is c\nt$ by
 *opp+  its fl[ into cycles ( action1   
repeat$ indef9itely & c\nt$ by a        
cumulat+ device4 ,) its *>act]i/ic (    
sav+ up en]gy = a  consid]able p]iod    
7ab\t #ae m9utes7 be=e lett+ x g 9 "o   
p[]ful action1 ! ,*9ese escapem5t 0     
p>ticul>ly suit$ to !  driv+ ( jackwork 
& o!r demon/ration devices requir+ mu*  
en]gy b only int]mitt5t activity4    ,9 
its f9al =m1 z built by ,su ,sung aft]  
_m trials &  improvem5ts1 ! ,*9ese      
a/ronomical clock-t[] mu/ h be5 a  mo/  
impressive object4 ,x _h ! =m ( a t[]   
ab\t #cj feet high1  surm\nt$ by an     
obs]vation plat=m cov]$ ) a light ro(   
7see  fig4 #d74 ,on ! plat=m 0 an       
armill>y sph]e design$ = obs]v+  !      
heav5s4 ,x 0 turn$ by ! clockwork s z to
 foll[ ! diurnal  rotation & ?us avoid !

 di/ress+ computations caus$ by !  *ange
 ( coord9ates necess>y :5 fix$          
alt-azimu? in/rum5ts 7  us$4 ,bel[ !    
plat=m 0 an enclos$ *amb] conta9+ !     
automatically rotat$ cele/ial globe :i* 
s wond]fully agre$ )  ! heav5s4 ,bel[   
?is1 on ! front ( ! t[] 0 a m9iature    
pagoda ) five ti]s2 on ea* ti] 0 a      
doorway ?r\gh :i*1 at due  mom5t1 appe>$
 jacks :o rang bells1 clang$ gongs1 beat
 drums1 &  held tablets to ann\nce !    
arrival ( ea* h\r1 ea* qu>t] 7!y  us$   
#ajj ( !m to ! day7 & ea* wat* ( !      
night4 ,)9 !  t[] 0 conceal$ ! me*anism2
 x consi/$ ma9ly ( a c5tral  v]tical    
%aft provid+ p[] = ! sph]e1 globe1 &    
jack:eels1  & a horizontal %aft ge>$ to 
! v]tical "o & c>ry+ ! great  wat] :eel 
:i* seem$ to set itself magically 9     
motion at e  qu>t]4 ,9 addition to all  
?is 7 ! lev]s ( ! escapem5t  me*anism & 
a pair ( norias by :i*1 once ea* day1 ! 
wat] us$  0 pump$ f a sump at ! bottom  
to a res]voir at ! top1 :5ce  x desc5d$ 
to "w ! :eel by means ( a con/ant level 

tank &  sev]al *annels4    ,!re 7 _m    
(f%oots & developm5ts ( ?is ma9 /em (   
,*9ese  horology4 ,we are told1 =       
example1 t (t5 m]cury & occasionally  s&
 7 us$ to replace ! wat]1 :i* frequ5tly 
froze 9 w9t] 9  spite ( ! application ( 
light$ brazi]s to ! int]ior ( !  ma*9es4
 ,!n aga91 ! a/ronomical models & !     
jackwork 7  !mselves subject to gradual 
improvem5t3 at ! "t ( ,i-,hs+1 =        
example1 special att5tion 0 paid to !   
dem>cation ( ecliptic z  well z ! normal
 equatorial coord9ates2 ?is 0 cle>ly an 
influx  f ,hell5i/ic-,islamic a/ronomy1 
9 :i* ! relatively  sophi/icat$ planet>y
 ma!matics _h =c$ ?is *ange n o!rwise   
not$ 9 ,*9a4    ,by ! "t ( ! ,jesuits1  
?is curr5t ( ,*9ese horology1 long s9ce 
utt]ly de/roy$ by ! p]ils ( w>s1 /orms1 
& gov]nm5tal  re=ms1 _h q be5 =gott54   
,matteo ,ricci's clocks1 ^? gifts  t    
ar\s$ s mu* m int]e/ ?an ,european      
!ological tea*+s1  7 obvi\sly some?+ q  
new to ! #af?-c5tury ,*9ese s*ol>s2  s  
mu* s t !y 7 dubb$ ) a q new "n1        

self-s\nd+  bells1 a direct translation 
( ! ^w clock 7glokke74 ,9 view (  ! fact
 t ! m$ieval ,*9ese escapem5t may h be5 
! basis (  ,european horology1 x is a   
curi\s twi/ ( fate t ! high reg>d (  !  
,*9ese = ,european clocks %\ld h prompt$
 !m to op5 _!  doors1 previ\sly s       
c>efully & = s long kept clos$ aga9/ !  
=eign b>b>ians4    ,illu/ration3 ,figure
 #d4--;,,a/ronomical ,,clock ,,t[] ,,(  
,,su ,,sung 9  ,k'ai-f5g1 ca4 ,a4,d4    
#ajij1 f an orig9al draw+ by ,john      
,*ri/ians54 7,c\rtesy ( ,cambridge      
,univ]sity ,press47          ,me*aniz$  
,a/ronomical ,models    ,n[ t we h se5 !
 mann] 9 :i* me*aniz$ a/ronomical models
  develop$ 9 ,*9a1 we c detect a simil> 
l9e runn+ f  ,hell5i/ic "t1 ?r\gh ,india
 & ,islam to ! m$ieval ,europe t        
inh]it$ _! le>n+4 ,!re are _m diff]5ces1
 notably because (  ! especial          
developm5t ( t peculi> *>act]i/ic ( !   
,we/1  ma!matical a/ronomy1 condition$  
by ! almo/ accid5tal conflux (          
,babylonian ari?metical me?ods ) ^? (   

,greek geometry4 ,h[ev]1  ! l9es are    
surpris+ly simil>1 ) ! exception only ( 
!  crucial inv5tion ( ! escapem5t1 a    
feature :i* seems to be  replac$ by !   
influx ( ideas connect$ ) p]petual      
motion :eels4      ,,hell5i/ic ,,p]iod  
,mo/ int]e/+ & frequ5tly cit$ is !      
bronze planet>ium said to  h be5 made by
 ,ar*im$es & describ$ 9 a tantalis+ly   
fragm5t>y fa%ion by ,cic]o & by lat]    
au?ors4 ,because ( its  importance z a  
prototype1 we give ! mo/ relevant       
passages 9  full4#aa    ,cic]o's        
descriptions ( ,ar*im$es' planet>ium are
 7italics suppli$73      ,gaius         
,sulpicius ,gallus 444 at a "t :5 444 he
 happ5$    to be at ! h\se ( ,m>cus     
,m>cellus1 8 colleague 9    ! consul%ip 
#aff ,b4,c41 ord]$ ! cele/ial globe to  
be br\ght out :i* ! gr&fa!r ( ,m>cellus 
_h    c>ri$ (f f ,syracuse1 :5 t v ri* &
    beautiful city 0 tak5 #bab          
,b4,c44444 ,?\gh ,i _h he>d    ?is globe
 7spha]ae7 m5tion$ q frequ5tly on       
acc\nt ( ! fame ( ,ar*im$es1 :5 ,i saw x

 ,i did n    p>ticul>ly admire x2 = t   
o!r cele/ial globe1    also con/ruct$ by
 ,ar*im$es1 :i* ! same ,m>cellus        
plac$ 9 ! temple ( ,virtue1 is m        
beautiful z well    z m widely kn[n     
among ! p4 ,b :5 ,gallus    began to    
give a v le>n$ explanation ( ! device1  
,i    conclud$ t ! fam\s ,sicilian _h   
be5 end[$ )    great] g5ius ?an "o w\ld 
imag9e possible = human    be+ to       
possess4 ,= ,gallus told u t ! o!r k9d  
( cele/ial globe1 :i* 0 solid & conta9$ 
no    holl[ space1 0 a v e>ly inv5tion1 
! fir/ "o (    t k9d hav+ be5 con/ruct$ 
by ,?ales ( ,miletus1    & lat] m>k$ by 
,eudoxus ( ,cnidus--a disciple (        
,plato1 x 0 claim$--) con/ellations &   
/>s :i*    are fix$ 9 ! sky4 ,he also   
said t _m ye>s lat]    ,aratus 444 _h   
describ$ x 9 v]se4444 ,b ?is new]    k9d
 ( globe1 he said1 on :i* 7 del9eat$ !  
motions ( ! sun & moon & ( ^? five />s  
:i*    are call$ w&]]s1 or1 z we might  
say1 rov]s    i4 e41 ! five planets1    
conta9$ m ?an c\ld be    %[n on ! solid 

globe1 & ! inv5tion ( ,ar*im$es         
des]v$ special admiration because he _h 
?\ght out a    way to repres5t          
accurately by a s+le device = turn+    !
 globe1 ^? v>i\s & div]g5t movem5ts )   
_! diff]5t rates ( spe$4 ,& :5 ,gallus  
mov$    i4e41 set 9 motion ! globe1 x 0 
actually true    t ! moon 0 always z _m 
revolutions beh9d !    sun on ! bronze  
contrivance z w\ld agree ) !    numb] ( 
days x 0 beh9d 9 ! sky4 ,?us ! same     
eclipse ( ! sun happ5$ on ! globe z w\ld
 actually    happ51 & ! moon came to !  
po9t :]e ! %ad[ (    ! e>? 0 at ! v "t  
:5 ! sun 7appe>$87    out ( ! region 444
 sev]al pages are miss+ 9 !             
manuscript2 !re is only "o4        ,de  
republica1 ,i1 xiv 7#ba-bb71 ,keyes'    
translation4      ,:5 ,ar*im$es put     
toge!r 9 a globe ! movem5ts (    ! moon1
 sun & five w&]+ planets1 he br\ght     
ab\t ! same effect z t :i* ! god (      
,plato did    9 ! ,timaeus :5 he made ! 
_w1 s t "o    revolution produc$        
dissimil> movem5ts ( delay &            

accel]ation4        ,tusculanae         
disputationes1 ,i1 #fc4    ,lat]        
descriptions f ,ovid1 ,lactantius1      
,claudian1 ,sextus ,empiricus1  &       
,pappus1 respectively1 are 7italics     
suppli$73      ,!re /&s a globe susp5d$ 
by a ,syracusan's skill 9    an enclos$ 
bronze frame1 or sph]e--or p]haps1 9    
enclos$ air1 a small image ( ! imm5se   
vault (    heav52 & ! e>? is equally    
di/ant f ! top &    bottom2 t is br\ght 
ab\t by its i4 e41 ! out]    bronze     
globe's r\nd =m4 ,! =m ( ! temple (     
,ve/a is simil>4444        ,ovid1 ,fa/i 
7#a/ c5tury1 ,a4,d471 ,,vi1 #bgg-bhj1   
,fraz]'s translation4      ,! ,sicilian 
,ar*im$es1 0 able to make a reproduction
    & model ( ! _w 9 concave brass      
7concavo a]e    similitud9em mundi ac   
figuram72 9 x he s arrang$ !    sun &   
moon & resembl+ ! cele/ial revolutions  
7caele/ibus similes conv]sionibus72 &   
:ile x    revolv$ x exhibit$ n only !   
accession & recession    ( ! sun & !    
wax+ & wan+ ( ! moon    7increm5ta      

dem9utionesque lunae71 b also ! unequal 
c\rses ( ! />s1 :e!r fix$ or w&]+4      
,lactantius1 ,in/itutiones div9ae 7#d?  
c5tury1 ,a4,d471        ,,ii1 #e1 #ah4  
,ar*im$es' sph]e4 ,:5 ,jove look$ d[n & 
saw !    heav5s figur$ 9 a sph]e (      
glass1 he laugh$ &    said to ! o!r     
gods3 ,has ! p[] ( mortal ef=t    gone s
 f>8 ,is my h&iwork n[ mimick$ 9 a      
fragile    globe8 ,an old man (         
,syracuse _h imitat$ on e>? !    laws ( 
! heav5s1 ! ord] ( nature1 & !          
ord9ances ( ! gods4 ,"s hidd5 influ5ce  
)9 !    sph]e directs ! v>i\s c\rses ( !
 />s &    actuates ! lifelike mass )    
def9ite motions4 ,a false    zodiac runs
 ?r\gh a ye> ( its own & a toy moon     
waxes & wanes mon? by mon?4 ,n[ bold    
inv5tion    rejoices to make its own    
heav5 revolve & sets !    />s planets8 9
 motion by human wit4444                
,claudian1 ,c>m9a m9ora 7ca4 ,a4,d4     
#djj71 ,,li 7,,lxviii71                 
,platnaure's translation4      ,! ?+s t 
move by !mselves are m wond]ful ?an     

^? :i* d n4 ,at any rate1 :5 we behold  
an    ,ar*im$ean sph]e 9 :i* ! sun & !  
re/ ( !    />s move1 we are imm5sely    
impress$ by x1 n by ,zeus    because we 
are amaz$ at ! wood1 or at ! movem5ts   
( ^! bodies1 b by ! devices & causes ( !
    movem5ts4        ,sextus ,empiricus1
 ,adv]sus ma!maticos 7#crd c5tury1      
,a4,d471 ,,ix1 #aae1 ,epps' translation4
      ,me*anics und]/& ! mak+ ( sph]es &
 "k h[ to    produce a model ( ! heav5s 
7) ! c\rses ( !    />s mov+ 9 circles87 
by mean ( equal & circul>    motions (  
wat]1 & ,ar*im$es ! ,syracusan1         
accord+ to "s1 kn[s ! cause & reasons = 
all (    ^!4      ,pappus 7#crd c5tury1 
,a4,d471 ,works 7,hults* edition71      
,,viii1 #b1 ,epps' translation4    ,a   
simil> arrangem5t seems to be indicat$ 9
 ano!r me*aniz$ globe1  also m5tion$ by 
,cic]o & said to h be5 made by          
,posidonius3      ,b if anyone br\ght to
 ,scy?ia or ,brita9 ! globe    7spha]am7
 :i* our fri5d ,posidonius ( ,apameia1 !
    ,/oic philosoph] rec5tly made1 9 :i*

 ea* revolution    produc$ ! same       
7movem5ts7 ( ! sun & moon &    five w&]+
 />s z is produc$ 9 ! sky ea* day    &  
night1 :o w\ld d\bt t x 0 by ex]tion (  
reason8444 ,yet d\bt]s 444 ?9k t        
,ar*im$es %[$    m k 9 produc+ movem5ts 
by revolutions ( a    globe ?an nature  
7does7 9 effect+ !m ?\gh ! copy    is s 
inf9itely inf]ior to ! orig9al4444      
,de natura deorum1 ,,ii1 xxxiv-xxxv     
7#hh71      ,yonge's translation4    ,9 
spite ( ! lack ( suffici5t te*nical     
details 9 any case1 ^!  me*aniz$ globe  
models1 ) or )\t ge>$ planet>y          
indicators  7:i* w\ld make !m highly    
complex ma*9es71 be> a /rik+            
resemblance to ! e>lie/ ,*9ese device   
describ$ by ,*ang ,hng4 ,"o  mu/ n      
reject ! possibility t transmission f   
,greece or ,rome  c\ld h rea*$ ! ,ea/ by
 ! beg9n+ ( ! #bnd c5tury1 ,a4,d41  :5  
he 0 work+4 ,x is an int]e/+ "q1 b ev5  
if su*  contact actually occurr$1 v soon
 aft]w>ds1 z we %all see1 !  we/]n &    
ea/]n l9es ( evolution p>t$ company &   

evolv$ s f>  z c be se51 q indep5d5tly  
until at lea/ ! #ab? c5tury4    ,! next 
,hell5i/ic s\rce ( :i* we mu/ take note 
is a fragm5t>y  & almo/ un9telligible   
*apt] 9 ! works ( ,h]o ( ,alex&ria4     
,alone & unconnect$ ) 8 o!r *apt]s ?is  
describes a model  :i* seems to be      
/atic1 9 direct contra/ to all o!r      
devices :i*  move by pneumatic &        
hydro/atic pressures2 x may well be     
conjectur$  t 9 its orig9al =m ?is *apt]
 describ$ a me*aniz$ r  ?an a /atic     
globe3      ,! ,_w repres5t$ 9 ! ,c5tre 
( ! ,univ]se3 ,!    con/ruction ( a     
transp>5t globe conta9+ air &    liquid1
 & also ( a small] globe1 9 ! c5tre1 9  
imitation ( ! ,_w4 ,two hemisph]es (    
glass are made2    "o ( !m is cov]$ ) a 
plate ( bronze1 9 !    middle ( :i* is a
 r\nd hole4 ,to fit ?is hole a light    
ball1 ( small size1 is con/ruct$1 & ?r[n
 into !    wat] conta9$ 9 ! o!r         
hemisph]e3 ! cov]$    hemisph]e is next 
appli$ to ?is1 &1 a c]ta9    quantity ( 
! liquid hav+ be5 remov$ f ! wat]1    ! 

int]m$iate space w conta9 ! ball2 ?us by
 !    application ( ! second hemisph]e  
:at 0 propos$ is    accompli%$4         
,pneumatics1 ,,xlvi1 ,woodcr(t's        
translation4    ,x w be not$ t ^! e>lie/
 lit]>y ref]5ces are conc]n$  )         
pictorial1 #c-;dim5sional models ( !    
univ]se1 mov$ p]haps by  h&1 p]haps by  
wat]p[]2 !re is no evid5ce t !y conta9$ 
complicat$ tra9s ( ge>s1 & 9 ! abs5ce ( 
?is we may incl9e  to ! view t 9 at lea/
 ! e>lie/ su* models1 ge>+ 0 n  us$4    
,! next developm5ts 7 conc]n$ on ! "o h&
 ) increas+ !  ma!matical sophi/ication 
( ! model1 on ! o!r h& ) its  me*anical 
complexity4 ,9 bo? cases we are mo/     
=tunate 9 hav+  ar*aeological evid5ce   
:i* f> exce$s any lit]>y s\rces4    ,!  
ma!matical process ( mapp+ a sph]e onto 
a plane surface by  /]eographic         
projection 0 introduc$ by ,hipp>*us & _h
 mu*  influ5ce on a/ronomical te*niques 
& in/rum5ts !reaft]4 ,9  p>ticul>1 by ! 
"t ( ,ptolemy 7ca4 ,a4,d4 #abj7 x _h l$ 
to !  successive inv5tions ( ! anaphoric

 clock & ( ! planisph]ic  a/rolabe4#ab  
,bo? ^! devices consi/ ( a pair (       
/]eographic  projections1 "o ( !        
cele/ial sph]e ) its />s & ecliptic &   
tropics1 ! o!r ( ! l9es ( altitude &    
azimu? z set = an  obs]v] 9 a place at  
"s p>ticul> latitude4    ,9 ! a/rolabe1 
an op5work metal rete conta9+ m>k+s = ! 
/>s1 etc41 may be rotat$ by h& ov] a    
disc on :i* ! l9es (  altitude & azimu? 
are inscrib$4 ,9 ! anaphoric clock a    
disc  engrav$ ) ! />s is rotat$         
automatically beh9d a fix$ grille  (    
wires m>k+ l9es ( altitude & azimu?4    
,p[] = rotat+ !  disc is provid$ by a   
float ris+ 9 a clepsydra j> & connect$1 
by  a rope or *a9 pass+ ov] a pulley to 
a c\nt]weight or by a rack  & p9ion1 to 
an axle :i* support$ ! rotat+ disc &    
communicat$ ?is motion to x4#ac         
,illu/ration3 ,figure #e4 ,,plate ,,(   
,,salzburg ,,anaphoric ,,clock1 a       
recon/ruction 7see footnote #ad7 bas$ on
 a photograph ( ! rema9+  fragm5t4      
7,c\rtesy ( ,ox=d ,univ]sity ,press47   

,p>ts ( two su* discs f anaphoric clocks
 h be5 f\nd1 "o at  ,salzburg#ad & "o at
 ,gr& 9 ! ,vosges1#ae bo? ( !m dat+  f !
 #bnd c5tury ,a4,d4 ,=tunately !re is   
suffici5t evid5ce to  recon/ruct !      
,salzburg disc & %[ t x mu/ h be5       
orig9ally  ab\t #agj cm4 9 diamet]1 a   
heavy %eet ( bronze to be turn$ by !    
small p[] provid$ by a float1 & a l>ge &
 impressive device :5  work+ 7see fig4  
#e74 ,lit]>y acc\nts ( ! anaphoric clock
 h be5  analyz$ by ,dra*mann2 !re is no 
evid5ce ( ! repres5tation (  planets    
mov$ ei!r by h& or by automatic ge>+1   
only 9 !  important case ( ! sun 0 su* a
 feature includ$ ( necessity4 ,a  model 
sun on a p9 c\ld be plugg$ 9 to any "o (
 #cfj holes drill$  9 at equal int]vals 
along ! b& ( ! ecliptic4 ,?is p9 c\ld be
  mov$ ea* day s t ! anaphoric clock    
kept /ep ) ! seasonal  v>iation ( !     
times ( sunrise & sunset & ! l5g?s ( day
 &  night4    ,! anaphoric clock is n   
only ! orig9 ( ! a/rolabe & ( all  lat] 
planet>y models1 x is also ! fir/ clock 

dial1 sett+ a  /&>d = clockwise         
rotation1 & leav+ its m>k 9 ! rotat+    
dial & /ation>y po9t] f\nd on ! e>lie/  
"t-keep+ clocks  be=e ! *ange 0 made to 
a fix$ dial & mov+ h&4    ,we come      
f9ally to a piece ( ar*aeological       
evid5ce t surpasses all  else4 ,?\gh    
badly pres]v$ & little /udi$ x might    
well be !  mo/ important classical      
object ev] f\nd2 entail+ a complete     
re-e/imation ( ! te*nical pr[ess ( !    
,hell5i/ic ,greeks4 ,9  #aija a sunk5   
treasure %ip 0 discov]$ ly+ (f ! isl& ( 
,antiky!ra1 betwe5 ,greece & ,crete4#af 
,_m beautiful classical  works ( /atu>y 
7 recov]$ f x1 & ^! are n[ among/ !     
greate/ treasures ( ! ,national ,museum 
at ,a!ns1 ,greece4 ,besides  ^! obvi\sly
 desirable art relics1 !re came to !    
surface "s  curi\s pieces ( metal1      
accompani$ by traces ( :at may h be5 a  
wood5 cas+4 ,two ?\s& ye>s "u ! sea _h  
r$uc$ ! metal to  a mess ( corrod$      
fragm5ts ( plates1 p[d]$ v]digris1 &    
/ill  recognizable pieces ( ge> :eels4  

,if x 7 n = ! e/abli%$ dates = o!r      
treasure f ?is  %ip1 especially ! m9or  
objects f\nd1 & = traces ( inscriptions 
on ?is metal device writt5 9 lett]s     
agree+ epigraphically ) !  o!r objects1 
"o w\ld h little d\bt 9 suppos+ t su* a 
complicat$ piece ( ma*9]y dat$ f ! #ah? 
c5tury1 at !  e>lie/4 ,z x is1 e/imates 
agree on ca4 #fe ,b4,c4 #aj ye>s1 & we  
c be sure t ! ma*9e is ( ,hell5i/ic     
orig91 possibly f  ,rhodes or ,cos4     
,illu/ration3 ,figure #f4--;,,antiky!ra 
,,ma*9e1 ,,l>ge/ ,,fragm5t4 7,photo     
c\rtesy ( ,national ,museum1 ,a!ns47    
,! inscriptions1 only p>tly legible1    
lead "o to believe t we are  deal+ ) an 
a/ronomical calculat+ me*anism ( "s     
sort4 ,?is is  born out by ! me*anical  
con/ruction evid5t on ! fragm5ts4 ,!    
l>ge/ "o 7fig4 #f7 conta9s a            
multiplicity ( ge>+ involv+ an  annul>  
ge> work+ epicyclic ge>+ on a turntable1
 a cr[n :eel1  & at lea/ f\r sep>ate    
tra9s ( small] ge>s1 z well z a         
#d-spok$ driv+ :eel4 ,"o ( ! small]     

fragm5ts 7fig4 #g1 bottom7  conta9s a   
s]ies ( movable r+s :i* may h s]v$ to   
c>ry  movable scales on "o ( ! ?ree     
dials4 ,! ?ird fragm5t 7fig4 #g1  top7  
has a pair ( r+s c>efully engrav$ &     
graduat$ 9 degrees (  ! zodiac 7?is is1 
incid5tally1 ! olde/ engrav$ scale kn[n1
 &  micrometric measurem5ts on          
photographs h indicat$ a maximum        
inaccuracy ( ab\t #a_/b 9 ! #de pres5t74
    ,illu/ration3 ,figure               
#g4--;,,antiky!ra ,,ma*9e1 ,,two        
,,small] ,,fragm5ts4  7,photo c\rtesy ( 
,national ,museum1 ,a!ns47              
,un=tunately1 ! v difficult task (      
clean+ ! fragm5ts is  sl[1 & no         
publication has yet giv5 suffici5t      
detail = an adequate  explanation ( ?is 
object4 ,"o c only say t al?\gh !       
problems  ( re/oration & me*anical      
analysis are peculi>ly great1 ?is mu/   
/& z ! mo/ important sci5tific artifact 
pres]v$ f  antiquity4    ,"s te*nical   
details c be glean$ h[ev]4 ,! %ape ( !  
ge>  tee? appe>s to be almo/ exactly    

equilat]al triangles 9 all cases  7fig4 
#h71 & squ>e %anks may be se5 at ! c5t]s
 ( "s ( !  :eels4 ,no :eel is q complete
 en\gh = a c\nt ( ge> tee?1 b  a        
provisional recon/ruction by ,!ophanidis
 7fig4 #i7 has %[n t !  appe>ances are  
consi/5t ) ! !ory t ! purpose ( !  ge>s 
0 to provide ! correct angul> ratios to 
move ! sun &  planets at _! appropriate 
relative spe$s4    ,illu/ration3 ,figure
 #h4--;,,antiky!ra ,,ma*9e1 ,,detail ,,f
 ,,figure #f1  %[+ ge>+4 7,photo c\rtesy
 ( ,national ,museum1 ,a!ns47    ,?us1  
if ! evid5ce ( ! ,antiky!ra ma*9e is to 
be tak5 at its  face value1 we h1       
already 9 classical times1 ! use (      
a/ronomical  devices z complicat$ z any 
clock4 ,9 any case1 ! mat]ial suppli$   
by ! works ascrib$ to ,ar*im$es1 ,h]o1 &
 ,vitruvius1 & ! m  c]ta9 evid5ce ( !   
anaphoric clocks is suffici5t to %[ t   
!re 0 a /rong classical tradition ( su* 
ma*9es1 a tradition  t inspir$1 ev5 if x
 did n directly influ5ce1 lat]          
developm5ts  9 ,islam & ,europe on ! "o 

side1 &1 j possibly1 ,*9a on !  o!r4    
,note add$ 9 pro(3      ,s9ce ! above   
l9es 7 writt51 ,i h be5 privileg$    to 
make a full exam9ation ( ! fragm5ts 9 ! 
,national ,museum 9 ,a!ns4 ,z a result  
we c read mu*    m inscription & make   
out _m m details ( !    me*anism4 ,!    
clean+ & dis5tangl+ ( ! fragm5ts    by !
 museum /aff has proce$$ to ! /age :]e  
"o    c ass]t mu* m positively t !      
device 0 an    a/ronomical comput] =    
sid]eal1 sol>1 lun>1 &    possibly also 
planet>y ph5om5a4 7,see my article 9 !  
,sci5tific ,am]ican1 ,june #aiei1 vol4  
#bjj1 ,no4 #f1 pp4    #fj-fg47 ,relevant
 to ! pres5t /udy1 x mu/ also be    not$
 at ?is po9t t ! ma*9e is n[ %[n to be  
/rongly relat$ to ! ge>$ a/rolabe (     
al-,biruni &    !reby ! ,hell5i/ic1     
,islamic1 & ,european    developm5ts are
 drawn toge!r ev5 m tightly4    ,let u  
n[ turn our att5tion to ^? civilizations
 :i* 7  int]m$i>ies1 geographically &   
culturally1 betwe5 ,greece &  m$ieval   
,europe1 & betwe5 bo? ( ^! & ,*9a4 ,f   

,india !re  are only two ref]5ces1 v    
closely relat$ & appe>+ 9 ! be/  kn[n   
a/ronomical texts 9 connection )        
descriptions ( !  armill>y sph]e &      
cele/ial globe4 ,^! texts are bo? q     
g>bl$1 b s f> z "o may und]/& !m1 x     
seems t ! types  ( sph]es & globes      
m5tion$ are m ak9 to ^? curr5t 9 ,*9a   
?an 9 ! ,we/4 ,! relevant portions (    
text are z foll[s 7italics  suppli$73   
,! circle ( ! horizon is midway ( !     
sph]e4 ,z    cov]$ ) a cas+ & z left    
uncov]$1 x is !    sph]e surr\nd$ by    
,lokloka ! m\nta9 range :i*    =m$ !    
b\nd>y ( ! univ]se 9 puranic geography4 
,by ! application ( wat] is made        
asc]ta9m5t ( !    revolution ( "t4 ,"o  
may con/ruct a sph]e-in/rum5t    comb9$ 
) quicksilv]3 ?is is a my/]y2 if pla9ly 
describ$1 x w\ld be g5]ally intelligible
 9 !    _w4 ,!re=e let ! supreme sph]e  
be con/ruct$    accord+ to ! in/ruction 
( ! preceptor guru4 ,9    ea* successive
 age ?is con/ruction1 hav+ become lo/1  
is1 by ! ,sun's fav\r1 aga9 reveal$ to  

"s "o or    o!r1 at 8 pleasure4 ,s also1
 "o %\ld con/ruct    in/rum5ts 9 ord] to
 asc]ta9 "t4 ,:5 q alone1    "o %\ld    
apply quicksilv] to ! wond]-caus+       
in/rum5t4 ,by ! gnomon1 /aff1 arc1 :eel1
 in/rum5ts    = tak+ ! %ad[ ( v>i\s     
k9ds4444 ,by    wat]-in/rum5ts1 !       
vessel1 by ! peacock1 man1    monkey1 & 
by /r+$ s&-receptacles "o may det]m9e   
"t accurately4 ,quicksilv]-holes1 wat]1 
& cords1 &    oil & wat]1 m]cury & s&   
are us$ 9 ^!3 ^!    applications1 too1  
are difficult4        ,srya ,siddhnta1  
xiii1 #ae-bb1        ,e4 ,burgess'      
translation1 ,new ,hav51 #ahfj4         
,illu/ration3 ,figure #i4--;,,antiky!ra 
,,ma*9e1 ,,p>tial ,,recon/ruction  ,,by 
,,!ophanidis 7see footnote #af74      ,a
 self-revolv+ in/rum5t or swayanvaha    
yantra3 ,make a    :eel ( light wood & 9
 its circumf]5ce put holl[    spokes all
 hav+ bores ( ! same diamet]1 & let !m  
be plac$ at equal di/ances f ea* o!r2 & 
let    !m also be plac$ at an angle v]g+
 some:at f !    p]p5dicul>3 !n half fill

 ^! holl[ spokes )    m]cury2 ! :eel ?us
 fill$ w1 :5 plac$ on an    axis        
support$ by two po/s1 revolve ( itself4 
,or scoop out a canal 9 ! tire ( ! :eel 
& !n    pla/]+ leaves ( ! ,tla tree ov] 
?is canal )    wax1 fill "o half ( ?is  
canal ) wat] & ! o!r    half ) m]cury1  
till ! wat] beg9s to come out1 &    !n  
cork up ! orifice left op5 = fill+ !    
:eel4    ,! :eel w !n revolve ( itself1 
drawn ar\nd by !    wat]4               
,description ( a syphon3 ,make up a tube
 ( copp] or o!r    metal1 & b5d x 9 ! =m
 ( an ,ankus'a or elephant    hook1 fill
 x ) wat] & /op up bo? ends4 ,& !n      
putt+ "o end into a res]voir ( wat] let 
! o!r    end rema9 susp5d$ outside4 ,n[ 
uncork bo? ends4 ,!    wat] ( ! res]voir
 w be :olly suck$ up & fall    outside4 
,n[ atta* to ! rim ( ! be=e describ$    
self-revolv+ :eel a numb] ( wat]-pots1 &
 place !    :eel & ^! pots l ! wat] :eel
 s t !    wat] f ! l[] end ( ! tube fl[+
 into !m on    "o side %all set ! :eel 9
 motion1 impell$ by !    additional     

weight ( ! pots ?us fill$4 ,! wat]      
dis*>ge f ! pots z !y rea* ! bottom ( ! 
revolv+ :eel1 %\ld be drawn (f into !   
res]voir    be=e allud$ to by means ( a 
wat]-c\rse or pipe4      ,! self-revolv+
 ma*9e m5tion$ by ,lalla1 etc4    :i*   
has a tube ) its l[] end op5 is a vulg> 
ma*9e on acc\nt ( its be+ dep5dant1     
because t    :i* manife/s an +5i\s & n a
 ru/ic contrivance    is said to be a   
ma*9e4      ,& moreov] _m self-revolv+  
ma*9es are to be met    )1 b _! motion  
is procur$ by a trick4 ,!y are    n     
connect$ ) ! subject "u discussion4 ,i h
    be5 induc$ to m5tion ! con/ruction (
 ^!1 m]ely    because !y h be5 m5tion$  
by =m] a/ronom]s4       ,siddhnta       
,siromai1 xi1 #ej-eg1 ,l4 ,wilk9son's   
translation1 revis$ by ,bpu deva        
,s7h7/ri1        ,calcutta1 #ahfa4      
,be=e proce$+ to an inve/igation ( !    
cont5t ( ^! texts x  is ( consid]able   
importance to e/abli% dates = !m1 ?\gh  
!re  are _m difficulties 9 e/abli%+ any 
*ronology = ,h9du  a/ronomy4 ,! ,srya   

,siddhnta is kn[n to date1 9 its orig9al
  =m1 f ! e>ly ,middle ,ages1 ca4 #ejj4 
,! section 9 "q is  h[ev] q evid5tly an 
int]polation f a lat] rec5sion1 mo/     
probably t :i* e/abli%$ ! complete text 
z x n[ /&s2 x  has be5 v>i\sly dat$ z   
ca4 #ajjj to ca4 #aaej ,a4,d4 ,! date ( 
! ,siddhnta ,siromai is m c]ta9 = we "k 
x 0  writt5 9 ab\t #aaej by ,bhsk>a     
7born #aaad74 ,?us bo? ^!  passages mu/ 
h be5 writt5 )9 a c5tury ( ! great      
clock-t[]  made by ,su ,sung4 ,!        
te*nical details w lead u to suppose !re
 is  m ?an a temporal connection4    ,we
 h already not$ t ! armill>y sph]es &   
cele/ial globes  describ$ j be=e ^!     
extracts are m simil> 9 design to       
,*9ese ?an to ,ptolemaic practice4 ,!   
m5tion ( m]cury & ( s&  z alt]natives to
 wat] = ! clock's fluid is ano!r feature
 v  preval5t 9 ,*9ese b abs5t 9 ! ,greek
 texts4 ,bo? texts seem  consci\s ( !   
complexity ( ^! devices & !re is a h9t  
7x is  lo/ & reveal$7 t ! /ory has be5  
transmitt$1 only half  und]/ood1 f ano!r

 age or culture4 ,x %\ld also be not$ t 
! m5tions ( cords & /r+s r ?an ge>s1 & !
 use (  sph]es r ?an planisph]es w\ld   
sugge/ we are deal+ )  devices simil> to
 ! e>lie/ ,greek models r ?an ! lat]    
devices1 or ) ! ,*9ese practice4    ,a q
 new & important note is inject$ by !   
passage f !  ,bhsk>a text4 ,obvi\sly    
intrusive 9 ?is a/ronomical text we h  !
 description ( two p]petual motion :eels
 toge!r ) a ?ird1  ca/igat$ by ! au?or1 
:i* helps its p]petuity by lett+ wat]   
fl[ f a res]voir by means ( a syphon &  
drop into pots ar\nd !  circumf]5ce ( ! 
:eel4 ,^! seem to be ! basis also1 9 !  
extract f ! ,srya ,siddhnta1 ( !        
wond]-caus+  in/rum5t to :i* m]cury mu/ 
be appli$4    ,9 ! next sections we %all
 %[ t ?is idea ( a p]petual motion      
device occurs aga9 9 conjunction )      
a/ronomical models 9 ,islam &  %ortly   
aft]w>ds 9 m$ieval ,europe4 ,at ea*     
occurr5ce1 z "h1  !re are e*oes ( o!r   
cultures4 ,9 addition to ^? already     
m5tion$ we f9d ! o!rwise my/]i\s        

peacock1 man & monkey1  cit$ z p>ts ( ! 
jackwork ( a/ronomical clocks ( ,islam1 
associat$ ) ! weight drive s ess5tial to
 ! lat] horology 9  ,europe4    ,we h   
already se5 t 9 classical times !re 7   
already two  diff]5t types (            
protoclocks2 "o1 :i* may be t]m$        
nonma!matical1 design$ only to give a   
visual aid 9 ! conception  ( ! cosmos1 !
 o!r1 :i* may be t]m$ ma!matical 9 :i*  
/]eographic projection or ge>+ 0 employ$
 to make ! device a  quantitative r ?an 
qualitative repres5tation4 ,^! two l9es 
occur aga9 9 ! ,islamic culture area4   
,nonma!matical protoclocks :i* are      
sc>cely remov$ f !  classical =ms appe> 
cont9u\sly ?r\gh ! ,byzant9e era & 9    
,islam z soon z x recov]$ f ! fir/ %ocks
 ( its =mation4  ,procopius 7di$ ca4    
#ece7 describes a monum5tal wat] clock  
:i* 0  erect$ 9 ,gaza ca4 #ejj4ag ,x    
conta9$ impressive jackwork1 su* z  a   
,m$usa head :i* roll$ its eyes e h\r on 
! h\r1 exhibit+  ! "t ?r\gh light$      
ap]tures & %[+ my?ological              

int]pretations ( ! cosmos4 ,all ^!      
effects 7 produc$ by  ,h]onic te*niques1
 us+ hydraulic p[] & puppets mov$ by    
/r+s1  r ?an ) ge>+4    ,aga9 9 #hjg a  
simil>ly m>vel\s exhibition clock made (
 bronze 0  s5t by ,h>un-al-,ra%id to !  
,emp]or ,*>lemagne2 x seems to h  be5 ( 
! same type1 ) automata & hydraulic     
works4 ,= !  succe$+ few c5turies1      
,islam 0 9 its ,gold5 ,age ( developm5t 
(  te*nical a/ronomy 7ca4 #iej-aaej7 &  
att5tion may h be5  conc5trat$ on ! m   
ma!matical protoclocks4 ,t[>ds ! end (  
! #ab? c5tury1 h[ev]1 !re 0 a revival ( 
! old tradition1  ma9ly at ! c\rt ( !   
,emp]or ,salad9 7#aadf-aagc7 :5 a great 
automaton wat] clock1 m magnific5t ?an  
any hi!rto1 0 erect$  9 ,damascus4 ,x 0 
rebuilt1 aft] #aafh1 by ,muammad b4 ',al
 b4  ,ru/um1 & repair$ & improv$ by 8   
son1 ,fakhr ad-dn  ,riwn b4 ,muammad1#ah
 :o is mo/ important z ! au?or (  a book
 :i* describes 9 consid]able te*nical   
detail ! con/ruction  ( ?is & o!r       
protoclocks4 ,closely associat$ ) 8 book

 "o also  f9ds texts deal+ )            
p]petual-motion devices1 :i* we %all    
consid] lat]4    ,dur+ ! c5tury foll[+  
?is horological exub]ance 9 ,damascus1  
! c5t] ( gravity ( ,islamic a/ronomy    
%ift$ f ! ,ea/ to !  ,hispano-,moori%   
,we/4 ,at ! same "t !re comes m evid5ce 
t  ! l9e ( ma!matical protoclocks _h n  
be5 left unatt5d$4 ,?is  is sugge/$ by a
 description giv5 by ,tri!mius ( ano!r  
royal gift  f ,ea/ to ,we/ :i* seems to 
h be5 diff]5t f ! automata  & hydraulic 
devices ( ! tradition f ,procopius to   
,riwn3#ai      ,9 ! same ye> #abcb !    
,salad9 ( ,egypt s5t by 8    ambassadors
 z a gift to ! emp]or ,fr$]ic a valuable
    ma*9e ( wond]ful con/ruction wor? m 
?an five    ?\s& ducats4 ,= x appe>$ to 
resemble int]nally a    cele/ial globe 9
 :i* figures ( ! sun1 moon1 &    o!r    
planets =m$ ) ! greate/ skill mov$1 be+ 
impell$ by weights & :eels1 s t p]=m+ _!
    c\rse 9 c]ta9 & fix$ int]vals !y    
po9t$ out !    h\r night & day )        
infallible c]ta9ty2 also !    twelve    

signs ( ! zodiac ) c]ta9 appropriate    
*>act]s1 mov$ ) ! firmam5t1 conta9$ )9  
!mselves ! c\rse ( ! planets4           
,illu/ration3 ,figure                   
#aj4--;,,cal5drical ,,ge>+ ,,design$    
,,by ,,al-,,biruni1  ca4 ,a4,d4 #ajjj4  
,! ge> tra9 c\nt is                     
#dj-ajg-eiai-eibd-dh4 ,!  ge> ( #dh     
!re=e makes #ai 7annual7 rotations :ile 
t ( #ai-ei  %[s #aah d\ble lunations (  
#bicjei days4 ,! ge> ( #dj %[s a  7lun>7
 rotation 9 exactly #bh days1 & ! c5t]  
p9ions #gaj rotate  9 exactly "o week4  
,aft] ,wi$emann 7see footnote #bj74     
,! phrase resembl$ int]nally is (       
especial int]e/ 9 ?is  passage2 x may   
p]haps arise z a mi/ranslation ( !      
te*nical t]m  = /]eographic projection (
 ! sph]e1 & if s ! device might  h be5  
an anaphoric clock or "s o!r a/rolabic  
device4    ,?is is made m probable by ! 
exi/5ce ( a specifically ,islamic       
conc5tration on ! a/rolabe1 & on its    
planet>y companion  in/rum5t1 !         
equatorium1 z devices = me*aniz+        

computation by  use ( geometrical       
analogues4 ,! ord9>y planisph]ic        
a/rolabe1 (  c\rse1 0 kn[n 9 ,islam f   
its fir/ days until almo/ ! pres5t  "t4 
,f ! "t ( al-,biruni 7ca4               
#ajjj7--significantly1 p]haps1  he is   
well kn[n = 8 travel acc\nt (           
,india--!re is rem>kable  innovation4   
,mo/ cog5t to our purpose is a text1    
describ$ = ! fir/ "t by  ,wi$emann1#bj 9
 :i* al-,biruni expla9s h[ a special    
tra9 (  ge>+ may be us$ to %[ !         
revolutions ( ! sun & moon at _!        
relative rates & to demon/rate ! *ang+  
phase ( ! moon1  features ( fundam5tal  
importance 9 ! ,islamic 7lun>7          
cal5drical  sy/em4 ,?is device          
necess>ily uses ge> :eels ) an odd numb]
 (  tee? 7e4g41 #g1 #ai1 #ei7 z dictat$ 
by ! a/ronomical con/ants  involv$ 7see 
fig4 #aj74 ,! tee? are %ap$ l equilat]al
 triangles  & squ>e %anks are us$1      
exactly z ) ! ,antiky!ra ma*9e4         
,horse-head$ w$ges are us$ = fix+2 a    
tradition borr[$ f !  horse-%ap$ ,f>s   

us$ to fa/5 ! traditional a/rolabe4 ,(  
special int]e/ = u is ! lun> phase      
diagram1 :i* is j !  same 9 =m &        
/ructure z ! lun> volvelle t occurs lat]
 9  horology & is /ill s commonly f\nd  
today1 especially z a  decoration = !   
dial ( gr&fa!r clocks4    ,illu/ration3 
,figure #aa4--;,,ge>$ ,,a/rolabe ,,by   
,,mu,,ammad ,b4 ,,ab ,,bakr  ,,(        
,,isfahan1 ,a4,d4 #abba-abbb4 7,photo   
c\rtesy ( ,sci5ce ,museum1  ,london47   
,biruni's cal5drical ma*9e is ! e>lie/  
complicat$ ge>$ device  on record & x is
 !re=e all ! m significant t x c>ries a 
feature f\nd 9 lat] clocks4 ,f !        
manuscript description alone "o  c\ld n 
tell :e!r x 0 design$ = automatic action
 or m]ely to  be turn$ by h&4 ,=tunately
 ?is po9t is made cle> by ! mo/  happy  
survival ( an intact specim5 ( ?is v    
device1 )\t d\bt  ! olde/ ge>$ ma*9e 9  
exi/5ce 9 a complete /ate4              
,illu/ration3 ,figure #ab4--;,,ge>+ ,,f 
,,a/rolabe ,,%[n ,,9 ,,figure #aa4  ,!  
ge> tra9 c\nt is z foll[s3              

#dh-ach-fdfd-fdaj-fj4 ,! p9ion  ( #h has
 be5 incorrectly replac$ by a m mod]n   
p9ion ( #aj4 ,!  ge> ( #dh %\ld make #ac
 7lun>7 rotations :ile ! d\ble ge> (    
#fdfd makes #f revolutions ( d\ble mon?s
 7( #bi-cj days7 & ! ge>  ( #fj makes a 
s+le turn 9 ! hegiral ye> ( #ced days4  
7,photo  c\rtesy ( ,sci5ce ,museum1     
,london47    ,?is l&m>k 9 ! hi/ory (    
sci5ce & te*nology is n[ pres]v$  at !  
,museum ( ! ,hi/ory ( ,sci5ce1 ,ox=d1   
,engl&4#ba ,x is an  a/rolabe1 dat$     
#abba-bb & sign$ by ! mak]1 ,muammad b4 
,ab  ,bakr 7di$ #abca-cb7 ( ,isfahan1   
,p]sia 7see figs4 #aa & #ab74 ,! v      
close resemblance to ! design ( ,biruni 
is q app>5t1 ?\gh !  ge>+ has be5       
simplifi$ v clev]ly s t only "o :eel has
 an  odd numb] ( tee? 7#ac71 ! re/ be+  
mu* easi] to m>k out  geometrically     
7e4g41 #aj1 #dh1 #fj1 & #fd tee?74 ,!   
lun> phase  volvelle c be se5 ?r\gh !   
circul> op5+ at ! back ( !  a/rolabe4 ,x
 is q c]ta9 t no automatic action is    
int5d$2  :5 ! c5tral pivot is turn$1 by 

h&1 probably by us+ !  a/rolabe rete z a
 h&le1 ! cal5drical circles & ! lun>    
phase are mov$ accord+ly4 ,us+ "o turn =
 a day w\ld be too sl[  = useful        
re-sett+ ( ! in/rum5t1 9 practice a turn
 corresponds  m ne>ly to an int]val ( "o
 week4    ,illu/ration3 ,figure         
#ac4--;,,a/rolabe ,,clock1 ,,regulat$   
,,by ,a ,,m]cury ,,drum1  f ! ,alfons9e 
,libros del sab] 7see footnote #bb74    
,9 addition to ?is ge>$ developm5t ( !  
a/rolabe1 ! same p]iod  9 ,islam br\ght 
=? a new device1 ! equatorium1 a        
me*anical model  design$ to simulate !  
geometrical con/ructions us$ = f9d+ !   
positions ( ! planets 9 ,ptolemaic      
a/ronomy4 ,! me?od may h  orig9at$      
already 9 classical times1 a simple     
device be+ describ$  by ,proclus        
,diado*us 7ca4 #dej71 b ! fir/ g5]al1   
?\gh crude1  planet>y equatorium seems  
to h be5 describ$ by ,abulcacim         
,abnacahm  7ca4 #ajbe7 9 ,granada2 x has
 be5 h&$ d[n to u 9 ! ar*aic  ,ca/ilian 
( ! ,alfons9e ,libros del sab]4#bb ,!   

sections ( ?is  book1 deal+ ) ! ,lam9as 
de las ,,vii ,planetas1 describe n only 
?is in/rum5t b also ! improv$           
modification introduc$ by  ,az>*iel     
7born ca4 #ajbi1 di$ ca4 #ajhg74    ,no 
,islamic examples ( ! equatorium h      
surviv$1 b f ?is  p]iod onw>d1 !re      
appe>s to h be5 a long & active         
tradition (  !m1 & ultimately !y 7      
transmitt$ to ! ,we/1 along ) !  re/ ( !
 ,alfons9e corpus4 ,m important = our   
argum5t is t  !y 7 ! basis = ! me*aniz$ 
a/ronomical models ( ,ri*>d (  ,wall+=d 
7ca4 #acbj7 & probably o!rs1 & = !      
already  m5tion$ great a/ronomical clock
 ( de ,dondi4 ,9 fact1 ! complicat$     
ge>work & dials ( de ,dondi's clock     
con/itute a s]ies ( equatoria1  me*aniz$
 9 j ! same way z ! cal5drical device   
describ$ by  ,biruni4    ,x is evid5t t 
we are com+ ne>] n[ to ! beg9n+ ( ! true
  me*anical clock1 & our la/ /ep1 also f
 ! ,alfons9e corpus (  we/]n ,islam1    
provides u ) an important l9k betwe5 !  
anaphoric  clock1 ! weight drive1 & a   

mo/ curi\s p]petual-motion device1 !    
m]cury :eel1 us$ z an escapem5t or      
regulator4 ,! ,alfons9e book on  clocks 
conta9s descriptions ( five devices 9   
all1 f\r ( !m be+  due to ,isaac b4 ,sid
 7two sundials1 an automaton wat]-clock 
& !  pres5t m]cury clock7 & "o to       
,samuel ha-,levi ,adulafia 7a c&le      
clock7--!y 7 probably compos$ j be=e ca4
 #abgf-gg4    ,illu/ration3 ,figure     
#ad4--;,,islamic ,,p]petual ,,motion    
,,:eel1 aft]  manuscript cit$ by        
,s*mell] 7see footnote #bf74    ,!      
m]cury clock ( ,isaac b4 ,sid consi/s ( 
an a/rolabe dial1 rotat$  z 9 !         
anaphoric clock1 & fitt$ ) #cj leaf-%ap$
 ge> tee?  7see fig4 #ac74 ,^! are driv5
 by a p9ion ( #f leaves m\nt$ on a      
horizontal axle 7%[n v diagrammatically 
9 ! illu/ration7 & at  ! o!r end ( ?is  
axle is a :eel on :i* is m\nt$ ! special
  m]cury drum :i* is p[]$ by a normal   
weight drive4    ,x is ! m]cury drum :i*
 =ms ! mo/ novel feature ( ?is  device2 
! fluid1 con/ra9$ 9 #ab *amb]s s z to j 

fill #f (  !m1 mu/ sl[ly filt] ?r\gh    
small holes 9 ! con/ra9+ walls4  ,9     
practice1 ( c\rse1 ! top m]cury surfaces
 w n be level1 b  high] on ! "r s z to  
balance dynamically ! mom5t ( !  appli$ 
weight on its driv5 rope4 ,?is curi\s   
arrangem5t %[s po9t  ( resemblance to ! 
,indian m]cury-holes1 to !              
p]petual-motion  devices f\nd 9 !       
m$ieval ,european tradition & also 9 !  
texts  associat$ ) ,riwn1 :i* we %all   
next exam9e4    ,illu/ration3 ,figure   
#ae4--;,,ano!r ,,p]petual ,,motion      
,,:eel1 aft] !  text cit$ 9 figure #ad4 
,x is ( ! greate/ int]e/ to our !me t ! 
,islamic  contributions to horology &   
p]petual motion seem to =m a closely    
knit corpus4 ,a mo/ important s]ies (   
horological texts1 includ+  ^? ( ,riwn &
 al-,jaz>1 h be5 edit$ by ,wi$emann  &  
,haus]4#bc ,o!r ,islamic texts give     
v]sions ( ! wat] clocks  & automata (   
,ar*im$es & ( ,h]o & ,philo (           
,alex&ria4#bd ,9  at lea/ ?ree cases#be 
^! texts are f\nd also associat$ )      

texts describ+ p]petual-motion :eels &  
o!r hydraulic devices4  ,?ree           
manuscripts ( ?is type h be5 publi%$ 9  
,g]man translation  by ,s*mell]4#bf ,!  
devices include a _m *amb]$ :eel 7see   
fig4  #ad7 simil> to ! ,alfons9e m]cury 
escapem5t1 a :eel ( slant+  tubes       
con/ruct$ l ! noria 7see fig4 #ae71     
:eels ( weights  sw++ on arms z describ$
 by ,vill>d ( ,honnec\rt1 & a rem>kable 
device :i* seems to be ! e>lie/ kn[n    
example ( a weight drive4  ,?is latt]   
ma*9e is a pump1 9 :i* a *a9 ( buckets  
is us$ to  raise wat] by pass+ ov] a    
pulley :i* is ge>$ to a drum p[]$  by a 
fall+ weight 7see fig4 #af72 p]haps =   
balance1 ! :ole  arrangem5t is made 9   
duplicate ) common axles = ! correspond+
  p>ts4    ,illu/ration3 ,figure        
#af4--;,,islamic ,,pump ,,p[]$ ,,by ,a  
,,weight ,,drive1  aft] ! text cit$ 9   
figure #ad4    ,! ,islamic tradition (  
wat] clocks did n involve ! use ( ge>s1 
?\gh v occasionally a pair is us$ to    
turn p[] ?r\gh an angle  :5 ?is is      

dictat$ by ! use ( a wat] :eel 9 !      
automata4 ,9  ! ma91 ev]y?+ is work$ by 
floats & /r+s or by hydraulic or        
pneumatic =ces1 z 9 ,h]os devices4 ,!   
automata are v elaborate1  ) figures (  
m51 monkeys1 peacocks1 etc41 symboliz+ !
 passage (  h\rs4      ,,m$ieval        
,,europe    ,e*oes f ne>ly all !        
developm5ts already not$ f o!r p>ts  ( !
 _w are f\nd to occur 9 m$ieval ,europe1
 (t5 com+  ?r\gh *annels ( communication
 m precisely det]m9able ?an  ^? hi!rto  
m5tion$4 ,be=e ! influx ( ,islamic le>n+
 at !  "t ( transmission ( ! ,tol$o     
,tables 7#ab? c5tury7 & !  ,alfons9e    
,tables 7:i* rea*$ ,p>is ca4 #abib71 !re
 are occasional  ref]5ces to ! mo/      
primitive me*aniz$ visual aids 9        
a/ronomy4    ,! mo/ fam\s ( ^! occurs 9 
an hi/orical acc\nt by ,ri*] (  ,rheims 
ab\t 8 tea*] ,g]b]t 7born #idf1 lat]    
,pope ,sylve/] ,,ii1  #iij-ajjc74       
,sev]al in/rum5ts made by ,g]b]t are    
describ$ 9 detail2  he includes a f9e   
cele/ial globe made ( wood cov]$ )      

horsehide  & hav+ ! />s & l9es pa9t$ 9  
color1 & an armill>y sph]e  hav+ sight+ 
tubes simil> to ^? always f\nd on ,*9ese
  in/rum5ts b nev] on ! ,ptolemaic      
v>iety4 ,la/ly1 he cites !  con/ruction 
( a sph]e1 mo/ suitable = recogniz+ !   
planets1  b un=tunately x is n cle> f ! 
description :e!r or n  ! model planets 7
 actually to be animat$ me*anically4 ,! 
text  runs3#bg      ,)9 ?is oblique     
circle 7! zodiac on ! ecliptic (    !   
globe7 he hung ! circles ( ! w&]+ />s 7!
    planets7 ) m>vell\s +5uity1 ^:      
orbits1 heights    & ev5 ! di/ance f ea*
 o!r he demon/rat$ to    8 pupils mo/   
effectually4 ,j h[ he accompli%$ ?is    
x is unsuitable to ent] into "h because 
( its ext5t    le/ we %\ld appe> to be  
w&]+ f our ma9 !me4    ,?us1 al?\gh !re 
is a h9t ( me*anical complexity1 !re is 
really  no ju/ification = su* an        
assumption2 ! description might well    
imply only a zodiac b& on :i* ! orbits (
 ! planets 7  pa9t$4 ,on ! o!r h& x is n
 inconceivable t ,g]b]t c\ld  h le>n$   

some?+ ( ,islamic & o!r extra-,european 
traditions  dur+ 8 p]iod ( /udy ) !     
,bi%op ( ,b>celona--a travel+  s*ol>%ip 
t seems to h _h _m rep]cussions on !    
:ole field  ( ,european s*ol>%ip4       
,once ! floodgates ( ,arabic le>n+ 7    
op5$1 a /ream (  me*aniz$ a/ronomical   
models p\r$ into ,europe4 ,a/rolabes &  
equatoria rapidly became v popul>1 ma9ly
 ?r\gh ! reason =  :i* !y _h be5 fir/   
devis$1 ! avoidance ( t$i\s writt5      
computation4 ,_m m$ieval a/rolabes h    
surviv$1 & at lea/ ?ree  m$ieval        
equatoria are kn[n4 ,*auc] is well kn[n 
= 8 treatise on  ! a/rolabe2 a          
manuscript 9 ,cambridge1 conta9+ a      
companion  treatise on ! equatorium1 has
 be5 t5tatively sugge/$ by !  pres5t    
au?or z also be+ ! "w ( ,*auc] & ! only 
piece  writt5 9 8 own h&4    ,! ge>$    
a/rolabe ( al-,biruni is ano!r type (   
protoclock to h  be5 transmitt$4 ,a     
specim5 9 ! ,sci5ce ,museum1 ,london1#bh
 ?\gh  un=tunately n[ incomplete1 has a 
v sophi/ocat$ arrangem5t (  ge>s = mov+ 

po9t]s to indicate ! correct relative   
positions &  movem5ts ( ! sun & moon    
7see figs4 #ag & #ah74 ,l ! e>li]       
,muslim example x conta9s :eels ) odd   
numb]s ( ge> tee? 7#ad1  #bg1 #ci72     
h[ev]1 ! tee? are no long] equilat]al 9 
%ape1 b  approximate a m mod]n slightly 
r\nd$ =m4 ,?is example is ,fr5*  &      
appe>s to date f ca4 #acjj4 ,ano!r      
,go?ic a/rolabe ) a  simil> ge> r+ on ! 
rete1 said to date f ca4 #adjj 7x c\ld  
well be mu* e>li]7 is n[ 9 ! ,billmei]  
collection 7,london74#bi    ,turn+ f !  
me*aniz$ a/rolabe to ! me*aniz$         
equatorium1 we  f9d ! "w ( ,ri*>d (     
,wall+=d 7#abib8-accf7 ( ! greate/      
int]e/ z provid+ an imm$iate precursor  
to t ( de ,dondi4 ,he  0 ! son ( an     
+5i\s blacksmi?1 mak+ 8 way to ,m]ton   
,college1 ,ox=d1 !n ! mo/ active &      
orig9al s*ool ( a/ronomy  9 ,europe1 &  
w9n+ lat] di/9ction z ,abbot ( ,/4      
,albans4 ,a text  by him1 dat$ #acbf-bg1
 describ$ 9 detail ! con/ruction ( a    
great  equatorium1 m exact & mu* m      

elaborate ?an any t _h gone  be=e4#cj   
,nev]!less x is evid5tly a normal       
manually op]at$  device l all ! o!rs4 ,9
 addition to ?is in/rum5t1 ,ri*>d is    
said to h con/ruct$ ca4 #acbj1 a f9e    
planet>y clock = 8  ,abbey4#ca ,bale1 :o
 seems to h se5 x1 reg>d$ x z )\t rival 
9 ,europe1 & ! greate/ curiosity ( 8 "t4
 ,un=tunately1 !  issue 0 confus$ by    
,lel&1 :o id5tifi$ x z ! ,albion 7i4e41 
all-by "o71 ! "n ,ri*>d gives to 8      
manual equatorium4 ,?is clock  0 inde$ s
 complex t ,edw>d ,,iii c5sur$ ! ,abbot 
= sp5d+ s  mu* money on x1 b ,ri*>d     
repli$ t aft] 8 dea? nobody w\ld  be    
able to make su* a ?+ aga94 ,he is said 
to h left a text  describ+ ! con/ruction
 ( ?is clock1 b ! abs5ce ( su* a  "w has
 l$ _m mod]n writ]s to support ,lel&'s  
id5tification &  suppose t ! device 0 n 
a me*anical clock4    ,illu/ration3     
,figure #ag4--;,,fr5* ,,ge>$ ,,a/rolabe 
,,( ,,trefoil ,,go?ic  ,,design1 ca4    
,a4,d4 #acjj4 ,! ge>+ on ! po9t] is1 f !
  c5t]3 7#cb7_/ad-debg-ci1 ! la/ me%+ ) 

a concave annul> ge>  ( #ahj tee? ar\nd 
! rim ( ! rete ( ! a/rolabe4 ,a second  
po9t]1 ge>$ to ?is s z to foll[ ! ,moon1
 seems to be lack+4  7,photo c\rtesy (  
,sci5ce ,museum4 ,london47              
,illu/ration3 ,figure #ah4--;,,ge>      
,,tra9 ,,( ,,po9t] 9 figure #ag4 7,photo
  c\rtesy ( ,sci5ce ,museum1 ,london47  
,a corrective = ?is view is to be _h f a
 ,/4 ,albans manuscript  7n[ at         
,gonville & ,caius ,college1 ,cambridge7
 t describ$ !  me?ods = sett+ out too!d 
:eels = an a/ronomical horologium       
design$ to %[ ! motions ( ! planets4    
,al?\gh ! manuscript  copy is to be dat$
 ca4 #acdj1 x cle>ly indicates t a ge>$ 
planet>y device 0 kn[n 9 ,/4 ,albans at 
an e>ly date1 & x is  reasonable to     
suppose t ?is 0 9 fact ! ma*9e made by  
,ri*>d  ( ,wall+=d4 ,un=tunately ! text 
does n appe> to give any  relevant      
in=mation ab\t ! pres5ce ( an escapem5t 
or any o!r  regulatory device1 nor does 
x m5tion ! s\rce ( p[]4#cb ,n[ a  ge>$  
v]sion ( ! ,albion w\ld appe> to        

correspond v closely  inde$ to ! dial-"w
 :i* =ms ! great] "p ( ! de ,dondi      
clock1 & = ?is reason we sugge/ n[ t !  
two clocks 7 v  closely relat$ 9 o!r    
ways too4 ,?is1 circum/antial ?\gh x be1
 is  evid5ce = ?9k+ t ! weight drive &  
"s =m ( escapem5t  7 kn[n to ,ri*>d (   
,wall+=d1 ca4 #acbj4 ,x w\ld n>r[ !  gap
 betwe5 ! clock & ! protoclocks to less 
?an half a c5tury1  p]haps a s+le       
g5]ation1 9 ! int]val ca4 #abhe-acbj4 ,9
 ?is  connection x may be ( int]e/ t    
,ri*>d ( ,wall+=d knew only  ! ,tol$o   
tables corpus1 t ( ! ,alfons9e s*ool did
 n arrive 9  ,engl& until aft] 8 dea?4  
,!re are1 ( c\rse1 _m lit]>y ref]5ces to
 ! wat]-clocks 9  m$ieval lit]ature4 ,9 
fact mo/ ( ^! are f quotations :i*  h   
(t5 be5 produc$ errone\sly 9 ! hi/ory ( 
! me*anical  clock1 !reby provid+ _m    
mislead+ />ts = t hi/ory1 z  not$       
previ\sly 9 ! discussion ( ! horologium4
 ,!re are h[ev]  en\gh m5tions to make x
 c]ta9 t wat] clocks ( "s sort 7  9 use1
 especially = ecclesia/ic purposes1 f ! 

end ( ! #ab?  c5tury onw>ds4 ,?us1      
,jocel9 ( ,brakelond tells ( a fire 9 ! 
,abbey  ,*ur* ( ,bury ,/4 ,edmunds 9 !  
ye> #aaih4cc ,! relics w\ld h  be5      
de/roy$ dur+ ! night1 b j at ! crucial  
mom5t !  clock bell s\nd$ = mat9s & !   
ma/] ( ! ve/ry s\nd$ !  al>m4 ,on ?is ! 
"y m5 among/ u ran to get wat]1 "s to ! 
well & o!rs to ! clock--probably ! sole 
occasion on :i* a  clock s]v$ z a fire  
hydrant4    ,x seems probable t "s ( ^! 
wat] clocks c\ld h be5 simple  drip     
clepsydras1 ) p]haps a /rik+ arrangem5t 
add$4 ,a mo/  =tunate discov]y by ,drov]
 has n[ br\ght to light a manuscript    
illum9ation t %[s t ^! wat] clocks1 at  
lea/ by ca1 #abhe1  _h become m complex 
& 7 r simil> 9 appe>ance to !  ,alfons9e
 m]cury drum4#cd ,! illu/ration 7fig4   
#ai7 is f a  moraliz$ ,bible writt5 9   
nor!rn ,france1 & accompanies ! passage 
:]e ,k+ ,hezekiah is giv5 a sign by !   
,"l1 ! sun be+ mov$  back t5 /eps ( !   
clock4 ,! picture cle>ly %[s ! c5tral   
wat]  :eel & bel[ x a dog's head sp\t   

gu%+ wat] into a bucket  support$ by    
*a9s1 ) a 7weight87 cord runn+ beh9d4   
,above !  :eel is a c>illon ( bells1 &  
to "o side a rosette :i* might be a  fly
 or a model sun4 ,! :eel appe>s to h #ae
 comp>tm5ts1 ea* )  a c5tral hole       
7p]haps simil> to t 9 ! ,alfons9e clock7
 & x  is support$ on a squ>e axle by a  
bracket1 ! axle be+ w$g$ 9 !            
traditional fa%ion4 ,! projections at ! 
edge ( ! :eel might be  ge> tee?1 b m   
likely !y are us$ only = tripp+ ! /rik+ 
me*anism4 ,if x 7 n = ! runn+ wat] sp\t 
x w\ld be v  close to ! ,alfons9e model2
 b ) ?is evid5ce x seems impossible  to 
arrive at a cle> me*anical              
int]pretation4    ,f ! adjac5t region   
!re is ano!r acc\nt ( a /rik+ wat]      
clock1 ! evid5ce be+ inscriptions on    
slates1 discov]$ 9 ,vill]s  ,abbey ne>  
,brussels2#ce ^! may be closely dat$ z  
#abfg or #abfh &  provide ! rema9s ( a  
memor&um = ! sacri/ & 8 assi/ants  9    
*>ge ( ! clock4      ,always set !      
clock1 h[ev] long y may delay on !      

lett] ,a aft]w>ds y %all p\r wat] f !   
little pot 7pottulo7 t is !re1 into !   
res]voir    7cacabum7 until x rea*es !  
prescrib$ level1 & y    mu/ d ! same :5 
y set ! clock aft] compl9e    s t y may 
sleep s\ndly4    ,a q diff]5t sort (    
evid5ce is to be _h f ! writ+s (        
,rob]tus ,anglicus 9 #abga :]e "o gets !
 impression t j at  ?is "t !re 0 active 
int]e/ 9 ! attempt to make a            
weight-driv5 anaphoric clock & to       
regulate its motion by "s  un/at$ me?od 
s t x w\ld keep "t ) ! diurnal rotation 
(  ! heav5s3#cf      ,nor x is possible 
= any clock to foll[ ! judgm5t (        
a/ronomy ) complete accuracy4 ,yet      
clockmak]s    7artifices horologiorum7  
are try+ to make a :eel    7circulum7   
:i* w make "o complete revolution =    e
 "o ( ! equ9octial circle1 b !y _c q    
p]fect _! "w4 ,b if !y c\ld1 x w\ld be a
    really accurate clock 7horologium   
v]ax valde7 & wor?    m ?an an a/rolabe 
or o!r a/ronomical in/rum5t    = reckon+
 ! h\rs1 if "o knew h[ to d ?is         

accord+ to ! me?od a=esaid4 ,! me?od (  
mak+    su* a clock w\ld be ?is1 t a man
 make a disc    7circulum7 ( uni=m      
weight 9 e "p s f> z c\ld    possibly be
 done4 ,!n a lead weight %\ld be hung f 
! axis ( t :eel 7axi ipsius rote7 & ?is 
weight    w\ld move t :eel s t x w\ld   
complete "o    revolution f sunrise to  
sunrise1 m9us z mu* "t z    ab\t "o     
degree rises accord+ to an approximately
    correct e/imate4 ,= f sunrise to    
sunrise1 ! :ole    equ9octial rises1 &  
ab\t "o degree m1 ?r\gh    :i* degree ! 
sun moves aga9/ ! motion ( !    firmam5t
 9 ! c\rse ( a natural day4 ,moreov]1   
?is    c\ld be done m accurately if an  
a/rolabe 7    con/ruct$ ) a network on  
:i* ! entire equ9octial    circle 0     
divid$ up4    ,illu/ration3 ,figure     
#ai4--,,manuscript ,,illum9ation ,,( ,a 
,,m$ieval  ,,wat]clock1 %[+ a p>tition$ 
:eel1 a weight drive1 & a c>illion  =   
/rik+4 ,f ,drov] 7see footnote #cd74    
,! text !n cont9ues ) te*nical          
a/ronomical details ( !  slight diff]5ce

 betwe5 ! rate ( rotation ( ! sun & ( ! 
fix$ />s 7because ( ! annual rotation ( 
! sun among/ !  />s7 b x gives no       
indication ( any regulatory device4     
,aga9 x  %\ld be not$1 ?is s\rce comes f
 ,france2 ,rob]tus1 ?\gh (  ,engli%     
orig91 app>5tly be+ !n a lectur] ei!r at
 !  ,univ]sity ( ,p>is or at t (        
,montpelli]4 ,! date ( ?is passage1     
#abga1 has be5 tak5 z a t]m9us po/ quem 
= ! inv5tion ( !  me*anical clock4 ,9 ! 
next section we %all describe ! text (  
,pet] ,p]egr9us1 v close to ?is 9 place 
& date1 :i* describes  j su* a ma*9e1   
conflat+ x ) acc\nts ( an armill>y      
sph]e1  p]petual motion1 & ! magnetic   
compass--s br++ all ^!  ?reads toge!r = 
! fir/ "t 9 ,europe4    ,illu/ration3   
,figure #bj4--;,,arrangem5t ,,= ,,turn+ 
,a ,,figure ,,( ,,an ,,angel4  ,x has   
be5 alleg$ t ?is draw+ by ,vill>d       
repres5ts an  escapem5t4 ,aft] ,lassus  
7see footnote #cg74    ,we h res]v$ to !
 la/ "o section ( evid5ce :i* may or may
  n be mislead+1 ! fam\s notebook (     

,vill>d 7,wil>s7 (  ,honnec\rt1 ne>     
,cambrai4 ,! album1 attribut$ to ! p]iod
 #abdj-abea1  conta9s _m draw+s ) %ort  
annotations1 ?ree ( :i* are (  special  
int]e/ to our inve/igations4#cg ,^!     
comprise a /eeplelike  /ructure label$  
ce/ li masons don orologe 7?is is ! h\se
 ( a  clock71 a device includ+ a rope1  
:eel & axle 7fig4 #bj71 m>k$ p>  *u fait
 om un angle t5ir son doit ades v]s le  
solel 7by ?is means  an angel is made to
 keep 8 f+] direct$ t[>ds ! sun71 & a   
p]petual motion :eel :i* we %all res]ve 
= lat] discussion4    ,! clock t[]1     
accord+ to ,drov]1 %[s no place = a dial
 b  sugge/s ! use ( bells because ( its 
op5 /ructure1 suitable =  lett+ out !   
s\nd4 ,moreov]1 he sugge/s t ! delicacy 
( !  l9e indicates t x 0 n really a     
full-size /eeple b r a  small t[]like   
/ructure /&+ only a few feet high )9 !  
*ur*4 ,!re is1 alas1 no?+ to tell u ab\t
 ! clock x 0  int5d$ to h\se2 mo/       
probably x 0 a wat] clock simil> to t ( 
! illu/rat$ ,bible ( ca4 #abhe4    ,!   

draw+ ( ! rope1 :eel & axles1 = turn+ an
 angel to po9t  t[>ds ! sun c h a simple
 explanation or a m complicat$ "o4  ,if 
tak5 at its face value ! :eel on its    
horizontal axis acts z a  w9dlass       
connect$ by ! c\nt]pois$ rope to !      
v]tical %aft :i*  x turns1 !reby mov+   
7by h&7 ! figure ( an angel 7n %[n7     
fix$ to ! top ( ?is latt] %aft4 ,su* an 
explanation 0 9 fact  sugge/$ by ,m4    
,qui*]at1#ch :o fir/ call$ att5tion to !
 ,vill>d  album & po9t$ out t a lead5   
angel exi/$ 9 ,*>tres be=e !  fire !re 9
 #ahcf4 ,x is a view also support$ f    
ano!r draw+ 9  ! album :i* describes an 
eagle ^: head is made to turn t[>ds  !  
deacon :5 he reads ! ,gospel4 ,slight   
pressure on ! tail ( !  bird causes a   
simil> rope me*anism to op]ate4    ,a q 
diff]5t int]pretation has be5 sugge/$ by
 ,frmont2#ci he  believes t ! :eel may h
 act$ z a fly-:eel & ! ropes &          
c\nt]poises1 turn+ fir/ "o way !n ! o!r 
act$ z a sort (  me*anical escapem5t4   
,su* an arrangem5t is h[ev] me*anically 

impossible )\t "s complicat$ free-:eel+ 
device betwe5 !  drive & ! escapem5t1 & 
its only effect w\ld be to oscillate !  
angel rapidly r ?an turn x /eadily4 ,i  
believe t ,frmont1  ov]-anxi\s to       
provide a protoescapem5t1 has done too  
mu* viol5ce to  ! facts & turn$ away )\t
 good reason f ! m simple &  reasonable 
explanation4 ,x is nev]!less /ill       
possible to adopt ?is  simple           
int]pretation & yet to h ! sy/em z "p ( 
a clock4 ,if  ! left-h& c\nt]poise1     
conv5i5tly rais$ high] ?an t on !  "r1  
is consid]$ z a float fitt+ into a      
clepsydra j>1 in/ead (  z a simple      
weight1 "o w\ld h a v suitable automatic
 sy/em =  turn+ ! angel4 ,on ?is        
explanation1 ! purpose ( ! :eel w\ld  be
 m]ely to provide ! manual adju/m5t     
necess>y to set ! angel  f "t to "t1    
comp5sat+ = irrem$iable inaccuracies ( !
  clepsydra4    ,illu/ration3 ,figure   
#ba4--,,vill>d',s ,,p]petual ,,motion   
,,:eel1 f ,lassus  7see footnote #cg74  
,hav+ discuss$ ! ,vill>d draw+s :i* are 

already cit$ 9  horological lit]ature1  
we mu/ draw att5tion to ! fact t ?is    
m$ieval ar*itect also gives an          
illu/ration ( a p]petual motion  :eel4  
,9 ?is case 7fig4 #ba7 x is ( ! type    
hav+ weights at !  end ( sw++ arms1 a   
type t occurs v frequ5tly at lat] dates 
9 ,europe & is also giv5 9 ! ,islamic   
texts4 ,we _c1 9 ?is  case1 sugge/ t    
draw+s ( clocks & ( p]petual motion     
devices  occur toge!r by m ?an a        
co9cid5ce1 = ,vill>d seems to h  be5    
int]e/$ 9 mo/ sorts ( me*anical device4 
,b ev5 ?is type  ( co9cid5ce becomes    
some:at /rik+ :5 repeat$ (t5 en\gh4 ,x  
seems t ea* e>ly m5tion ( self-mov+     
:eels occurs 9  connection ) "s sort (  
clock or me*aniz$ a/ronomical device4   
,hav+ n[ complet$ a survey ( !          
traditions ( a/ronomical models1  we h  
se5 t _m types ( device embody+ features
 lat] f\nd 9  me*anical clocks evolv$   
?r\gh v>i\s cultures & fl[$ into        
,europe1 com+ toge!r 9 a bur/ (         
multif>i\s activity dur+ !  second half 

( ! #ac? c5tury1 notably 9 ! region (   
,france4 ,we  mu/ n[ attempt to fill !  
residual gap1 & 9 s do+ exam9e !        
importance ( p]petual motion devices1   
me*anical & magnetic1 9 !  crucial      
transition f protoclock to              
me*anical-escapem5t clock4              
,p]petual ,motion & ! ,clock be=e de    
,dondi    ,we h already not$1 m or less 
briefly1 sev]al in/ances ( !  use (     
:eels mov+ by !mselves or ! use ( a     
fluid = purposes  o!r ?an z a motive    
p[]4 ,*ronologically arrang$1 ^! are !  
,indian devices ( ca4 #aaej or a little 
e>li]1 z ^? ( ,riwn  ca4 #abjj1 t ( !   
,alfons9e m]cury clock1 ca4 #abgb1 & !  
,fr5* ,bible illum9ation ( ca4 #abhe4   
,?is /rongly sugge/s a /eady            
transmission f ,ea/ to ,we/1 & on !     
basis ( x1 we n[  t5tatively propose an 
additional /ep1 a transmission f ,*9a to
  ,india & p]haps fur!r ,we/1 ca4 #aajj1
 & possibly re9=c$ by  fur!r            
transmissions at lat] dates4    ,"o ne$ 
only assume ! exi/5ce ( vague travel]'s 

tales ab\t !  exi/5ce ( ! #aa?-c5tury   
,*9ese clocks ) _! a/ronomical  models &
 jackwork & ) _! great :eel1 app>5tly   
mov+ by  itself b us+ wat] hav+ no      
ext]nal inlet or outlet4 ,su* a         
/imulus1 act+ z x did on a lat] occasion
 :5 ,galileo receiv$  ^w ( ! inv5tion ( 
! telescope 9 ! ,l[ ,c\ntries1 might    
easily lead to ! re-inv5tion ( j su*    
p]petual-motion :eels z  we h already   
not$4 ,9 _m ways1 once ! idea has be5   
sugge/$ x  is natural to associate su* a
 p]petual motion ) ! incessant  diurnal 
rotation ( ! heav5s4 ,)\t "s su* /imulus
 h[ev] x  is difficult to expla9 :y ?is 
association did n occur e>li]1 &  :y1   
once x comes !re seems to be su* a      
*ronological procession  f culture to   
culture4    ,we n[ turn to :at is       
und\bt$ly ! mo/ curi\s "p ( ?is /ory1  9
 :i* automatically mov+ a/ronomical     
models & p]petual motion  :eels are l9k$
 ) ! e>lie/ texts on magnetism & !      
magnetic  compass1 ano!r subject ) a    
s+ul>ly tr\bl$ hi/orical orig94  ,! key 

text 9 ?is is ! fam\s ,epi/le on !      
magnet1 writt5 by  ,pet] ,p]egr9us1 a   
,pic>d1 9 an army camp at ! ,siege (    
,luc]a &  dat$ ,augu/ #h1 #abfi4dj ,9   
spite ( ! precise dat+ x is c]ta9  t !  
"w 0 done long be=e1 = x is quot$       
unmi/akably by  ,rog] ,bacon 9 at lea/  
?ree places1 "o ( :i* mu/ h be5  writt5 
be=e ca4 #abej4da    ,! ,epi/le conta9s 
two p>ts2 9 ! fir/ !re is a g5]al       
acc\nt ( magnetism & ! prop]ties ( !    
load/one1 clos+ ) a  discussion ( !     
inquiry :5ce ! magnet receives ! natural
 virtue  :i* x has4 ,pet] attribut$ ?is 
virtue to a sympa?y ) !  heav5s1 propos+
 to prove 8 po9t by ! con/ruction ( a   
t]rella1 a uni=m sph]e ( load/one :i* is
 to be c>efully  balanc$ & m\nt$ 9 !    
mann] ( an armill>y sph]e1 ) its axis   
direct$ along ! pol> axis ( ! diurnal   
rotation4 ,he !n  cont9ues3      ,n[ if 
! /one !n move accord+ to ! motion ( !  
heav5s1 rejoice t y h arriv$ at a secret
 m>vel4    ,b if n1 let x be ascrib$ r  
to y\r own want (    skill ?an to a     

defect ( ,nature4 ,b 9 ?is position1 or 
mode ( plac+1 ,i deem ! virtues ( ?is   
/one to be    prop]ly cons]v$1 & ,i     
believe t 9 o!r positions    or p>ts ( !
 sky its virtue is dull$1 r ?an         
pres]v$4 ,by means ( ?is in/rum5t at all
 ev5ts y    w be reliev$ f e k9d ( clock
 7horologium71    = by x y w be able to 
"k ! ,asc5dant at    :atev] h\r y w1 &  
all o!r dispositions ( !    heav5s :i*  
,a/rolog]s seek aft]4    ,x %\ld be not$
 t ! device is to be m\nt$ l an         
a/ronomical  in/rum5t & us$ l "o1 r ?an 
z a "t tell]1 or z a  simple            
demon/ration ( magnetism4 ,9 ! second "p
 ( ! ,epi/le  ,pet] turns to practical  
in/rum5ts1 describ+ = ! fir/ "t1 !      
con/ruction ( a magnetic compass consi/+
 ( a load/one or iron  ne$le pivot$ ) a 
cas+ m>k$ ) a scale ( degrees4 ,! ?ird  
*apt] ( ?is section1 conclud+ ! ,epi/le1
 !n cont9ues )  ! description ( a       
p]petual motion :eel1 elab\r$ ) m>vell\s
  +5uity1 9 ! pursuit ( :i* inv5tion ,i 
h se5 _m p  w&]+ ab\t1 & we>i$ )        

manifold toil4 ,= !y did n  obs]ve t !y 
c\ld arrive at ! ma/]y ( ?is by means ( 
!  virtue1 or p[] ( ?is /one4    ,?is   
tells u incid5tally1 t ! p]petual motion
 device 0 a  subject ( consid]able      
int]e/ at ?is "t4#db ,oddly en\gh1 ,pet]
  does n n[ develop 8 idea ( ! t]rella1 
b proce$s to some?+  q new1 a device    
7see fig4 #bb7 9 :i* a b>-magnet        
load/one is to  be set t[>ds ! end ( a  
pivot$ radial arm ) a circle fitt$ on  !
 inside ) iron ge> tee?1 ! tee? be+ !re 
n to me%  ) o!rs b to draw ! magnet f "o
 to ! next1 a little bead  provid+ a    
c\nt]weight to help ! in]tia ( rotation 
c>ry !  magnet f "o po9t ( attraction to
 ! next4 ,x is by no means !  sort (    
device t "o w\ld naturally evolve z a   
means ( mak+  magnetism "w p]petually1 &
 ,i sugge/ t ! too!d :eel is  ano!r     
in/ance ( "s vague idea ( protoclocks1  
p]haps t ( ,su  ,sung1 be+ transmitt$ f 
! ,ea/4    ,illu/ration3 ,figure        
#bb4--,,magnetic ,,p]petual ,,motion    
,,:eel illu/rat$  by ,pet] ,p]egr9us2 f 

! edition ( ,s4 ,p4 ,?ompson 7see       
footnote  #dj74    ,! "w ( ,pet]        
,p]egr9us is cit$ by ,rog] ,bacon 9 8   
,de  secretis z well z 9 ! ,opus majus &
 ,opus m9us4 ,9 ! fir/  & e>lie/ ( ^!   
occurs a description1 tak5 f ,ptolemy1 (
 !  con/ruction ( ! 7obs]v+7 armill>y   
sph]e4 ,he says t ?is  _c be made to    
move naturally by any ma!matical device1
 b a  fai?ful & magnific5t exp]im5tor is
 /ra9+ to make "o out (  su* mat]ial1 & 
by su* a device1 t x w revolve naturally
 )  ! diurnal heav5ly rotation4 ,he     
cont9ues ) ! /atem5t t  ?is possibility 
is also sugge/$ by ! fact t ! motions ( 
comets1 ( tides1 & ( c]ta9 planets also 
foll[ t ( ! ,sun &  ( ! heav5s4 ,only 9 
! ,opus m9us1 :]e he repeats ref]5ce to 
?is device1 does he f9ally reveal t x is
 to be made to "w by  means ( !         
load/one4    ,! =m ( ,bacon's ref]5ce to
 ,p]egr9us is /rongly rem9isc5t (  !    
/atem5t by ,rob]tus ,anglicus1 already  
m5tion$ z an indication  ( preoccupation
 ) diurnally rotat+ :eels1 at a date    

7#abga7  rem>kably close to t ( !       
,epi/le 7#abfi7--s mu* s t x  c\ld well 
be ?\ght t ! fri5d to :i* ,pet] 0 writ+ 
0  ei!r ,rob]t himself or somebody      
associat$ ) him1 p]haps at !  ,univ]sity
 ( ,p>is--a natural place to :i* !      
it9]ant ,pet] might  communicate 8      
f9d+s4    ,! fundam5tal "q "h1 ( c\rse1 
is :e!r ! idea ( an  automatic          
a/ronomical device 0 transmitt$ f       
,arabic1 ,indian1 or  ,*9ese s\rces1 or 
:e!r x arose q indep5d5tly 9 ?is case z 
a natural concomitant ( id5tify+ ! poles
 ( ! magnet ) !  poles ( ! heav5s4 ,we  
%all n[ attempt to %[ t ! hi/ory (  !   
magnetic compass might provide a q      
indep5d5t argum5t 9  fav\r ( ! hypo!sis 
t !re 0 a '/imulus' transmission4       
,! ,magnetic ,compass z a ,fell[-travel]
 f ,*9a    ,! elusive hi/ory ( !        
magnetic compass has _m po9ts 9 common  
) t ( ! me*anical clock4 ,j z we h      
a/ronomical models  f ! e>lie/ times1 s 
we f9d k ( ! load/one & "s  ( its       
prop]ties4 ,!n1 p>allel to ! developm5t 

( protoclocks 9  ,*9a ?r\gh\t ! middle  
ages1 we h ! evid5ce analyz$ by         
,ne$ham1 %[+ ! use ( ! magnet z a       
div9atory device & ( !  7nonmagnetic7   
s\?-po9t+ *>iot1 :i* has be5 confus$ly  
alli$  to ! /ory4 ,curi\sly1 & p]haps   
significantly ! ,*9ese hi/ory  comes to 
a head at j ! same "t = compasses &     
clocks1 & a  prime au?ority = ! ,*9ese  
compass is ,%5 ,kua 7#ajcj-ajic7 :o also
  appe>s 9 connection ) ! clock ( ,su   
,sung1 & :o wrote ab\t !  me*aniz$      
armill>y sph]es & o!r models ca4 #ajhf4 
,ano!r simil>ity occurs 9 connection ) !
 hi/ory ( ! compass  9 m$ieval ,europe4 
,! treatise ( ,pet] ,p]egr9us1 already  
discuss$1  provides ! fir/ complete     
acc\nt ( ! magnetic compass ) a  pivot$ 
ne$le & a circul> scale1 & ?is1 z we h  
se51 may be  connect$ ) protoclocks &   
p]petual-motion devices4 ,!re are       
sev]al e>li] ref]5ces1 h[ev]1 to ! use (
 ! directive  prop]ties ( load/one1     
ma9ly = use 9 navigation1 b ^!  e>lie/  
texts h a long hi/ory ( errone\s        

int]pretation :i* is  only rec5tly be+  
cle>$ away4 ,we "k n[ t ! fam\s passages
  9 ! ,de naturis r]um & ,de ut5silibus 
( ,alex&] ,neckham#dc  7ca4 #aahg7 & a  
text by ,hugues de ,b]ze#dd 7aft] ca4   
#abjd7 ref]  to no?+ m ?an a float+     
magnet )\t pivot or scale1 b us+  a     
po9t] at "r angles to ! magnet1 s t x   
po9t$ to ! ea/1  r ?an ! nor? or s\?4 ,a
 simil> me?od is describ$ 7ca4  #abjj7 9
 a poem by ,guyot de ,prov9s1 & 9 a     
hi/ory ( ,j]usalem by  ,jacques de      
,vitry 7#abae74de ,x is ( ! greate/     
int]e/ t1 once  m1 all ! evid5ce seems  
to be conc5trat$ 9 ,france 7,neckham 0  
tea*+ 9 ,p>is7 ?\gh at an e>li] p]iod   
?an t = !  protoclocks4    ,! date might
 sugge/ ! "t ( ! fir/ great wave (      
transmissal  ( le>n+ f ,islam1 b x is   
cle> t 9 ?is in/ance1 peculi>  = t      
reason1 t ,islam le>n$ ( ! magnetic     
compass only aft]  x 0 already kn[n 9 ! 
,we/4 ,9 ! e>lie/ ,p]sian record1 "s    
anecdotes compil$ by al-',awfi ca4      
#abcj1df ! in/rum5t us$  by ! capta9    

dur+ a /orm at sea has ! =m ( a piece ( 
holl[  iron1 %ap$ l a fi% & made to     
float on ! wat] aft]  magnetization by  
rubb+ ) a load/one2 ! fi%like =m is v   
significant1 = ?is is di/9ctly ,*9ese   
practice4 ,9 a second ,muslim  ref]5ce1 
t ( ,bailak al-,qabjaq 7ca4 #abhb71 !   
ord9>y  wet-compass is t]m$ al-konbas1  
ano!r indication t x 0  =eign to t      
language & culture4#dg                  
,*ronological ,*>t                      
----------------------------------------
--------------------------------        
,,*9a      #d? ,c41 ,b4,c4 ,p[] ge>+    
,,classical ,,europe      #crd ,c41     
,b4,c4 ,ar*im$es planet>ium    #bnd ,c41
 ,b4,c4 ,hipp>*us ,/]eographic          
,projection    #a/ ,c41 ,b4,c4          
,vitruvius hodomet] & wat] clocks       
#fe1 ,b4,c4 7ca47 ,antiky!ra ma*9e      
#a/ ,c41 ,a4,d4 ,h]o hodomet] & wat]    
clocks    #bnd ,c41 ,a4,d4 ,salzburg &  
,vosges anaphoric clocks      ,,*9a     
#bnd ,c41 ,a4,d4 ,*ang ,hng animat$     
globe hodomet]        ,cont9u+ tradition

 ( animat$ a/ronomical models     #gbe  
,inv5tion ( ,*9ese escapem5t by ,i-,hs+ 
& ,liang ,l+-tsan      ,,islam          
#hjg ,h>un-al-,ra%id     #hej 7ca47     
,e>lie/ extant a/rolabes    #ajjj ,ge>$ 
a/rolabe ( al-,biruni      ,,europe     
#ajjj ,g]b]t a/ronomical model          
,,islam      #ajbe ,equatorium text     
,,*9a      #ajgd ,%5 ,kua1 clocks &     
magnetic compass    #ajhj ,su ,sung     
clock built    #aaja ,su ,sung clock    
de/roy$      ,,india      #aajj 7ca47   
,srya ,siddhnta animat$ a/ronomical     
models            & p]petual motion     
#aaej 7ca47 ,siddhnta ,siromai animat$  
models & p]petual            motion     
,,islam      #aaej ,salad9 clock        
,,europe      #aahg ,neckham on compass 
#aaih ,jocel9 on wat] clock      ,,islam
      #abjj 7ca47 ,riwn wat]-clocks1    
p]petual motion            & weight     
drive    #abjf al-,jaz> clocks1 etc4    
#abba ,ge>$ a/rolabe    #abcb ,*>lemagne
 clock    #abdc al-,konbas 7compass7    
,,europe      #abde ,vill>d clockt[]1   

escapem5t1 p]petual motion    #abfg     
,vill]s ,abbey clock    #abfi ,p]egr9us1
 compass & p]petual motion    #abga     
,rob]tus ,anglicus1 animat$ models &    
p]petual motion clock      ,,islam      
#abgb ,alfons9e corpus clock ) m]cury   
drum1 equatoria      ,,europe      #abhe
 ,drov]'s wat] clock ) :eel & weight    
drive    #acjj 7ca47 ,fr5* ge>$ a/rolabe
    #acbj ,ri*>d ( ,wall+=d a/ronomical 
clock & equatorium    #acfd de ,dondi's 
a/ronomical clock ) me*anical escapem5t 
lat] #ad? ,c4 ,tradition ( escapem5t    
clocks cont9ues      & deg5]ates into   
simple "t-keep]s                        
----------------------------------------
--------------------------------    ,!re
 is !re=e reasonable gr\nds = support+ !
 m$ieval  ,european tradition t !       
magnetic compass _h fir/ come f ,*9a1   
?\gh "o _c well admit t ! fir/ news ( x 
0 br\ght1 z  ! leg5d /ates1 by ,m>co    
,polo1 :5 he return$ home 9 #abfj4 ,!re 
might well h be5 ano!r wave ( int]e/1   
giv+ ! impetus to  ,pet] ,p]egr9us at   

?is "t1 b an e>li] transmission1 p]haps 
along ! silk road or by travel]s 9      
crusades1 mu/ be po/ulat$ to  acc\nt = !
 evid5ce 9 ,europe1 ca4 #abjj4 ,! e>li] 
influx does  n play any great "p 9 our  
ma9 /ory2 x arriv$ 9 ,europe be=e  !    
transmission ( a/ronomy f ,islam _h got 
"u way suffici5tly  to make protoclocks 
a subject ( int]e/4 ,= a second         
transmission1 we  h already se5 h[ !    
relevant texts seem to clu/]1 9 ,france 
ca4 #abgj1 ar\nd a complex 9 :i* !      
protoclocks seem comb9$ )  ! ideas (    
p]petual motion :eels & ) new in=mation 
ab\t !  magnetic compass4    ,! po9t (  
?is pap] is t su* a complex exi/s1 cutt+
 across  ! hi/ories ( ! clock1 ! v>i\s  
types ( a/ronomical ma*9es1  & !        
magnetic compass1 & includ+ ! orig9 (   
self-mov+  :eels4 ,x seems to trace a   
pa? ext5d+ f ,*9a1 ?r\gh ,india  & ?r\gh
 ,ea/]n & ,we/]n ,islam1 end+ 9 ,europe 
9 ! ,middle  ,ages4 ,?is pa? is n a     
simple "o1 = ! v>i\s elem5ts make _!    
appe>ances 9 diff]5t comb9ations f place

 to place1 sometimes "o  may be dom9ant1
 sometimes ano!r may be abs5t4 ,only by 
treat+ x z  a :ole has x be5 possible to
 produce ! ?reads ( cont9uity :i*  w1 ,i
 hope1 make fur!r rese>* possible1      
circumv5t+ ! bl9d  alleys f\nd 9 ! pa/ &
 lead+ ev5tually to a complete  und]/&+ 
( ! fir/ complicat$ sci5tific ma*9es4   
,,footnotes3      #a ,?is traditional   
view is express$ by almo/ e hi/ory    ( 
horology4 ,an ultimate s\rce = _m ( ^!  
has be5 !    foll[+ two classic         
treatm5ts3 ,j4 ,beckmann1 ,a hi/ory (   
inv5tions & discov]ies1 #d? ed41        
,london1 #ahdf1 vol4 #a1 pp4    #cdj ff4
 ,a4 ,p4 ,u%]1 ,a hi/ory ( me*anical    
inv5tions1 #bnd    ed41 ,h>v>d          
,univ]sity ,press4 #aied1 pp4 #aia ff41 
#cjd ff4      #b ,!re is a consid]able  
lit]ature deal+ ) ! lat]    evolution ( 
p]petual motion devices4 ,! mo/         
compreh5sive    treatm5t is ,h4 ,dircks1
 ,p]petuum mobile1 ,london1 #ahfa2 #bnd 
s]41 ,london1 #ahgj4 ,s f> z ,i "k !re  
has n previ\sly    be5 mu* discussion ( 

! hi/ory ( su* devices be=e !           
r5aissance4      #c ,= ! e>ly hi/ory (  
ge>+ 9 ! ,we/ see ,c4    ,mats*oss1     
,ges*i*te des ,zahnrades1 ,b]l91 #aidj4 
,also ,f4 ,m4    ,feldhaus1 ,die        
ges*i*tli*e ,entwicklung des ,zahnrades 
9    ,!orie und ,praxis1 ,b]l91 #aiaa4  
#d ,a g5]al acc\nt ( ^! important       
ar*aeological objects    w be publi%$ by
 ,j4 ,ne$ham1 ,sci5ce & civilisation 9  
,*9a1 ,cambridge1 #aiei7871 vol4 #d4 ,! 
orig9al publications    79 ,*9ese7 are z
 foll[s3 ,wang ,*5-to1 ,inve/igations & 
reproduction 9 model =m ( ! s\?-po9t+   
c>riage &    hodomet]1 ,national ,peip+ 
,academy ,hi/orical ,j\rnal1    #aicg1  
vol4 #c1 p4 #a4 ,liu ,hsi5-*\1 ,*9ese   
inv5tions 9    horological eng9e]+1     
,*'+-,hua ,univ]sity ,eng9e]+           
,j\rnal1 #aief1 vol4 #d1 p4 #a4      #e 
,= illu/rations ( int]me%+ worms 9      
,indian cotton    mills1 see ,mats*oss1 
op4 cit4 7footnote #c71 figs4 #e1 #f1   
#g1    p4 #g4      #f ,x is int]e/+ to  
note t ! ,*9ese hodomet] 0              

contempor>y ) t ( ,h]o & ,vitruvius & v 
simil>    9 design4 ,!re is no evid5ce  
:atsoev] ^u :i* to decide    :e!r !re   
may h be5 a specific transmission ( ?is 
inv5tion or ev5 a /imulus diffusion4    
#g ,a summ>y ( ! cont5t ( ! manuscript  
s\rces1    illu/rat$ by ! orig9al       
draw+s1 has be5 publi%$ by ,h4    ,alan 
,lloyd1 ,giovanni de ,dondi's           
horological ma/]piece1    #acfd1 )\t    
date or impr9t 78,lausanne1 #aiee71 #bc 
pp4 ,x    %\ld be rem>k$ t de ,dondi    
decl9es to describe !    work+s ( 8 cr[n
 & foliot escapem5t 7?\gh x is well     
illu/rat$7 say+ t ?is is ( ! common     
v>iety & if    ! read] does n und]/& su*
 simple ?+s he ne$ n    hope to         
compreh5d ! complexities ( ?is mighty   
clock4 ,b    ?is may be bravado to q a  
l>ge degree4      #h ,see1 = example1 ! 
*ronological tables ( ! #ad?    c5tury &
 ! lat] m5tions ( clocks 9 ,e4 ,z9n]1   
,aus d]    ,frhzeit d] ,rd]uhr1 ,muni*1 
#aied1 p4 #bi ff4 ,un=tunately    ?is v 
complete treatm5t t5ds to confuse !     

factual &    leg5d>y s\rces prior to !  
clock ( de ,dondi2 x also    accepts ! v
 d\btful evid5ce ( ! escapem5t drawn by 
,vill>d ( ,honnec\rt 7see p4 #ajg74 ,an 
excell5t & fully    illu/rat$ acc\nt (  
monum5tal a/ronomical clocks    ?r\gh\t 
! _w is giv5 by ,alfr$ ,ung]]1 ,les     
horloges    a/ronomiques1 ,/rasb\rg1    
#aica1 #ead pp4 ,available acc\nts (    
! developm5t ( ! planet>ium s9ce !      
middle ages are    v brief & especially 
weak on ! e>ly hi/ory3 ,helmut    ,w]n]1
 ,f ! ,aratus globe to ! ,zeiss         
planet>ium1    ,/uttg>t1 #aieg2 ,c4 ,a4 
,crommel91 ,planet>ia1 a hi/orical      
survey1 ,antiqu>ian ,horology1 #aiee1   
vol4 #a1 pp4 #gj-ge4      #i ,d]ek ,j4  
,price1 ,clockwork be=e ! clock1        
,horological    ,j\rnal1 #aiee1 vol4    
#ig1 p4 #haj1 & #aief1 vol4 #ih1 p4 #ca4
      #aj ,= ! use ( ?is mat]ial ,i am  
indebt$ to my    co-au?ors4 ,i mu/ also 
ackn[l$ge ?anks to ! ,cambridge         
,univ]sity ,press1 :i* 9 ! ne> future w 
be publi%+    our monograph1 ,heav5ly   

,clockwork4 ,"s ( ! f9d+s (    ?is pap] 
are includ$ 9 %ort] =m z backgr\nd      
mat]ial    = t monograph4 ,a brief      
acc\nt ( ! discov]y ( ?is    mat]ial has
 be5 publi%$ by ,j4 ,ne$ham1 ,wang ,l+1 
& ,d]ek    ,j4 ,price1 ,*9ese           
a/ronomical clockwork1 ,nature1 #aief1  
vol4 #agg1 pp4 #fjj-fjb4      #aa ,= ^! 
translations f classical au?ors ,i am   
indebt$ to ,pr(essor ,lor5 ,mac,kinney &
 ,miss ,h>riet ,latt91    :o _h collect$
 !m = a hi/ory1 n[ ab&on$1 (            
planet>iums4 ,i am grateful = !         
opportunity ( giv+ !m    "h ! m5tion !y 
des]ve4      #ab ,a4 ,g4 ,dra*mann1 ,!  
plane a/rolabe & ! anaphoric    clock1  
,c5taurus1 #aied1 vol4 #c1 pp4 #ahc-ahi4
      #ac ,a full] description ( !      
anaphoric clock & cognate    wat]-clocks
 is giv5 by ,a4 ,g4 ,dra*mann1          
,ktesibios1 ,philon    & ,h]on1 ,acta   
,hi/orica ,sci5ti>um ,naturalium et     
,m$ic9alium1 ,cop5hag51 #aidh1 vol4 #d4 
#ad ,fir/ publi%$ by ,o4 ,b5ndorf1 ,e4  
,weiss1 & ,a4 ,rehm1    ,jahre%efte des 

/]rei*is*5 ar*ologis*5 ,in/itut 9       
,wi51 #aijc1 vol4 #f1 pp4 #cb-di4 ,i h  
giv5 fur!r details (    its con/ruction 
9 ,a hi/ory ( te*nology1 ed4 ,s+]1      
,holmy>d1 & ,hall1 #aieg1 vol4 #c1 pp4  
#fjd-fje4      #ae ,l4 ,maxe-,w]ly1     
,mmoires de la ,socit ,nationale des    
,antiquaires de ,france1 #ahhg1 vol4    
#dh1 pp4 #agj-agh4      #af ,! fir/     
def9itive acc\nt ( ! ,antiky!ra ma*9e   
0 giv5 by ,p]ikles ,r$iadis 9 ,j4       
,svoronos1 ,das ,a!n]                   
,nationalmuseum1 ,a!ns1 #aijh1 ,textb&  
,i1 pp4 #dc-ea4 ,s9ce    !n1 o!r        
photographs 7mo/ly v poor7 h appe>$1 &  
an attempt at a recon/ruction has be5   
made by ,re> ,admiral    ,jean          
,!ophanidis1 ,praktika tes ,akademias   
,a!non1 ,a!ns1    #aicd1 vol4 #i1 pp4   
#adj-adi 79 ,fr5*74 ,i am deeply        
grateful to    ! ,director ( ! ,a!ns    
,national ,museum1 ,m4 ,k>\zos1 =       
provid+ me ) an excell5t new set (      
photos1 f :i*    figures #f-h are n[    
tak54      #ag ,h4 ,diels b] die von    

,prokop bes*rieb5e ,kun/uhr von         
,gaza1 ,abh&lung51 ,akademie d]         
,wiss5s*aft51 ,b]l91    ,philos4-,hi/4  
,klasse1 #aiag1 ,no4 #g4      #ah ,l4   
,a4 ,may]1 ,islamic a/rolabi/s & _!     
works1    ,g5eva1 #aief1 p4 #fb4        
#ai ,! translation :i* foll[s is quot$ f
 ,j4 ,beckmann1    op4 cit4 7footnote   
#a71 p4 #cdi4      #bj ,e4 ,wi$emann1   
,e9 ,in/rum5t das die ,bewegung von     
,sonne    und ,mond d>/ellt1 na* al     
,biruni1 ,d] ,islam1 #aiac1 vol4 #d1    
p4 #e4      #ba ,i ackn[l$ge ) ?anks to 
! ,curator ( t museum    ! p]mission to 
reproduce photographs ( ?is in/rum5t4 ,x
    is item #e 9 ,r4 ,t4 ,gun!r1        
,a/rolabes ( ! _w1 ,ox=d1    #aicb4     
#bb ,abulcacim ,abnacahm1 ,libros del   
sab]1 edition by ,rico y    ,s9obas1    
,madrid1 #ahff1 vol4 #c1 pp4 #bda-bga4  
,! design ( !    in/rum5t has be5 v     
fully discuss$ by ,a4 ,weg5]1 ,die      
a/ronomis*5 ,w]ke ,alfons ,x1 ,biblio!ca
 ,ma!matica1    #aije1 pp4 #abi-ahi4 ,a 
m complete discussion ( ! hi/orical     

evolution ( ! equatorium is giv5 9 ,d]ek
 ,j4 ,price1 ,!    equatorie ( !        
planetis1 ,cambridge 7,eng471 #aiee1 pp4
    #aai-acc4      #bc ,e4 ,wi$emann1 & 
,f4 ,haus]1 b] die ,uhr5 im ,b]ei* d4   
islamis*5 ,kultur1 ,nova ,acta2         
,abh&lung5 d] knigli*e                  
,leopold9is*-,c>ol9is*e ,deuts*e        
,akademie d] ,natur=s*]    zu ,halle1   
#aiae1 vol4 #ajj1 no4 #e4      #bd ,e4  
,wi$emann1 & ,f4 ,haus]1 ,die ,uhr des  
,ar*im$es und    zwei &]e ,vorri*tung51 
,halle1 #aiah4      #be ,! manuscripts 9
 "q are z foll[s3 ,go?a1 ,kat4 v4       
,p]ts*4 #c1 #ah1 no4 #acdh2 ,ox=d1 ,cod4
 #ied2 ,leid51 ,kat4 #c1    #bhh1 no4   
#adad1 ,cod4 #dii ,w>n2 & ano!r simil>1 
,kat4 #c1 #bia1    no4 #adae1 ,cod4 #ic 
,gol4      #bf ,h4 ,s*mell]1 ,beitrge   
zur ,ges*i*te d] ,te*nik 9 d]    ,antike
 und bei d5 ,arab]n1 ,erlang51 #aibb    
7,abh&lung5 zur    ,ges*i*te d]         
,naturwiss5s*aft5 und d] ,m$iz9 no4 #f74
      #bg ,once m ,i am indebt$ to      
,pr(essor ,lor5 ,mac,kinney &    ,miss  

,h>riet ,latt9 7see footnote #aa7 = mak+
 _!    collections on ,g]b]t available  
to me4      #bh ,item #aih 9 ,gun!r1 op4
 cit4 7footnote #ba74 ,i am    grateful 
to ! au?orities ( t museum = p]mission  
to    reproduce photographs ( ?is       
in/rum5t4      #bi ,so!by & ,co41       
,london1 sale ( ,m>* #ad1 #aieg1 lot    
#aed4    ,! out] rim ( ! rete has #abj  
tee?4      #cj ,! ,lat9 text ( !        
treatise on ! ,albion1 has be5          
transcrib$ by ,rev4 ,h4 ,salt] & publi%$
 9 ,r4 ,t4 ,gun!r1    ,e>ly sci5ce 9    
,ox=d1 ,ox=d1 #aibc1 vol4 #b1 pp4       
#cdi-cgj4    ,an analysis ( its design  
is giv5 9 ,price1 op4 cit4    7footnote 
#bb71 pp4 #abg-acj4      #ca ,su*       
evid5ce z !re is = ! exi/5ce & =m (    !
 clock is collect$ by ,gun!r1 op4 cit4  
7footnote #cj71 p4    #di4      #cb ,i h
 discuss$ ?is new manuscript s\rce 9    
,two    m$ieval texts on a/ronomical    
clocks1 ,antiqu>ian ,horology1    #aief1
 vol4 #a1 no4 #aj1 p4 #aef4 ,!          
manuscript 9 "q is ms4    #bcj_/aaf1    

,gonville & ,caius ,college1 ,cambridge1
 folios    #aa-ad  pp4 #ca-cf4      #cc 
,! ,*ronicle ( ,jocel9 ( ,brakelond 4441
 ,h4 ,e4 ,butl]    7ed471 ,london1      
#aidi1 p4 #ajf4      #cd ,c4 ,b4 ,drov]1
 ,a m$ieval mona/ic wat]-clock1         
,antiqu>ian ,horology1 #aied1 vol4 #a1  
no4 #e1 pp4 #ed-eh1 #fc4    ,because ?is
 wat] clock uses :eels & /rikes bells "o
 mu/    reject ! evid5ce ( lit]>y       
ref]5ce1 su* z by ,dante1    f :i* !    
m5tion ( :eels & bells h be5 tak5 z     
positive pro( ( ! exi/5ce ( me*anical   
clocks )    me*anical escapem5ts4 ,!    
to-&-fro motion ( ! me*anical    clock  
escapem5t is q an impressive feature1 b 
!re    seems to be no lit]>y ref]5ce to 
x be=e ! "t ( de    ,dondi4      #ce    
,annales de la ,socit ,royale           
d',ar*ologie de ,bruxelles1    #ahif1   
vol4 #a_/h1 pp4 #bjc-bae1 #djd-dea4 ,!  
translation "h is    cit$ f ,drov]1 op4 
cit41 7footnote #cd71 p4 #ef4      #cf  
,l4 ,?orndike1 ,! sph]e ( ,sacrobosco & 
its    comm5tators1 ,*icago1 #aidi1 pp4 

#ahj1 #bcj4      #cg ,! album 0 publi%$ 
) facsimiles by ,j4 ,b4 ,a4    ,lassus1 
#aheh4 ,an ,engli% edition ) facsimiles 
( #cc ( !    #da folios 0 publi%$ by    
,rev4 ,rob]t ,willis1 ,ox=d1 #ahei4 ,an 
ext5sive summ>y ( ?is section is giv51 )
 illu/rations1    by ,j4 ,drummond      
,rob]tson1 ,! evolution ( clockwork1    
,london1    #aica1 pp4 #aa-ae4      #ch 
,m4 ,jules ,qui*]at1 ,revue             
,ar*ologique1 #ahdi1 vol4 #f4      #ci  
,m4 ,c4 ,frmont4 ,orig9e de l'horloge   
poids1 ,p>is1    #aiae4      #dj ,= ?is1
 ,i h us$ & quot$ f ! v beautiful       
edition 9 ,engli%1 prep>$ by ,silvanus  
,p4 ,?ompson1 ,london1    ,*iswick      
,press1 #aijb4      #da ,see ,e4 ,g4 ,r4
 ,taylor1 ,! ,s\?-po9t+ ne$le1 ,imago   
,mundi1 ,leid51 #aiea1 vol4 #h1 pp4 #a-g
 7especially pp4 #a1 #b74      #db ,i h 
wond]$ :e!r ! m$ieval int]e/ 9 p]petual 
motion c\ld be connect$ ) ! use ( !     
,:eel (    ,=tune 9 *ur*es z a sub/itute
 = bell-r++ on ,good    ,friday4        
,un=tunately ,i c f9d no evid5ce = or   

aga9/ !    conjecture4      #dc ,w4 ,e4 
,may1 ,alex&] ,neckham & ! pivot$       
compass    ne$le1 ,j\rnal ( ! ,in/itute 
( ,navigation1 #aiee1 vol4    #h1 no4   
#c1 pp4 #bhc-bhd4      #dd ,w4 ,e4 ,may1
 ,hugues de ,b]ze & ! m>9]'s compass1   
,! ,m>9]'s ,mirror1 #aiec1 vol4 #ci1 no4
 #b1 pp4 #ajc-ajf4      #de ,h4 ,balm]1 
,beitrge zur ,ges*i*te d] ,erk5ntnis des
    ,erdmagnetismus1 ,a>au1 #aief1 p4   
#eb4      #df ,! collection is ! ,gami  
'al ,hikajat2 ! relevant    passage be+ 
giv5 9 ,g]man translation 9 ,balm]4 op4 
cit4    7footnote #de71 p4 #ed4      #dg
 ,balm]1 op4 cit4 7footnote #de71 p4    
#ec4        ,u4,s4 ,,gov]nm5t ,,pr9t+   
,,(fice3 #aiei